MEETINGS AND CONFERENCES

CONFERENCE ON MAGNETISM

From November 26 to December 2, 1951, the Division of Physico-Mathematical Sciences of the USSR Academy of Sciences and the Ural Branch of the USSR Academy of Sciences (Institute of Metal Physics—Commission on Magnetism of the USSR Academy of Sciences) convened a conference on magnetism in Sverdlovsk.

This was the first broad conference of magnetism physicists in the five years since the “magnetic” conference held in Sverdlovsk in December 1946. About 300 physicists specializing in magnetism, electrical engineers, and metallurgists took part in the work of the conference, which lasted seven days; they represented various scientific institutions, industrial enterprises, and higher educational establishments in 20 different cities of the Soviet Union—Moscow, Leningrad, Sverdlovsk, Kharkov, Kiev, Kazan, Riga, Molotov, Chelyabinsk, Krasnoyarsk, Ashkhabad, and others.

At 6 plenary and 20 sectional sessions, about 80 reports were presented on various questions of magnetism. The 20 reports heard at the plenary sessions were devoted to general theoretical questions of magnetism or to experimental and methodological questions of broad interest to all participants in the conference. The agenda of the first section of the conference included reports on the atomic theory of magnetism, the study of the physical properties of magnetic substances in high-frequency fields, and nonmetallic ferromagnets (ferrites or oxyfers). The reports of the second section of the conference were devoted mainly to questions of the study of the properties of ferromagnetic materials—the theory of the technical magnetization curve, investigations of the influence of various external actions on the magnetic properties of ferromagnetic materials, methods of magnetic structural analysis, magnetic flaw detection, and magnetic calculations.

On the problems of the quantum theory of ferromagnetism, a general report was delivered by Prof. S. V. Vonsovskii. The report emphasized that all magnetic phenomena belong to the group of essentially quantum phenomena (the van Leeuwen—Terletsky theorem), and therefore one must treat with great caution various kinds of “quasi-classical” interpretations of the magnetic properties of matter. From the standpoint of Soviet science, overestimation of these purely illustrative interpretations contradicts dialectical materialism and is a metaphysical distortion of science. Such an enthusiasm for “quasi-classical” “theories” of ferromagnetism is characteristic of Anglo-American physicists. From the general foundations of quantum mechanics it follows that the ferromagnetic state of a substance can arise only starting from certain minimum dimensions ($\sim 10^{-7}$ cm). To construct a more exact theory of ferromagnetism it is necessary to take into account the interaction between electrons in the crystal. Neglect of this interaction is a fundamental error-

...theory. The most fruitful method for calculating quantum problems of ferromagnetism is the method of second quantization, which, for the case of small perturbations of the system, permits the introduction of quasiparticles, thereby greatly facilitating mathematical calculations without violating their rigor. The principal unresolved questions of the quantum theory of ferromagnetism were noted (the criterion of ferromagnetism, the fractional character of atomic moments, the laws of magnetic interaction, etc.). As one of the methods of solution, a theory is proposed of interacting external and internal electrons of ferromagnetic metals of the transition groups. Further development and refinement of such a theory is necessary. Special reports were devoted to concrete applications of this theoretical model of ferromagnets (see below).

In the report by Candidate of Physico-Mathematical Sciences S. V. Tyablikov, “On the Question of the Quantum Theory of Magnetic Anisotropy,” a calculation was presented of the magnetization curves and constant magnetic anisotropy energy of ferromagnetic single crystals on the basis of a rigorous quantum-mechanical account of the magnetic interaction between ferromagnetic electrons. The author uses the most consistent calculation scheme, developed by him jointly with Corresponding Member of the Academy of Sciences of the USSR N. N. Bogolyubov. The successful application of such a scheme opens up broad prospects for considering quantum problems in the theory of ferromagnetism, in which it is practically always necessary to take into account the magnetic interaction between electrons.

The report by Prof. S. V. Vonsovskii and Candidate of Physico-Mathematical Sciences K. B. Vlasov, “Atomic Magnetic Moments in Ferromagnetic Metals and Alloys,” was devoted to presenting the results of applying a model of interacting external and internal electrons to the problem of calculating atomic magnetic moments in ferromagnetic metals and alloys. Owing to the interaction between the internal electrons of ferromagnetism and the external conduction electrons, the latter become “magnetized” and therefore take part in creating the spontaneous magnetic moment in a ferromagnet. The “share” of the participation of the conduction electrons in the magnetization depends on the magnitude of their interaction with the internal electrons and may vary irregularly from metal to metal. The “fractional character” of the atomic magnetic moments is also determined by the joint participation of external and internal electrons in the spontaneous magnetization of ferromagnets. In the case of alloys this effect is further affected by the dependence on the composition of the alloy and on the order of arrangement of the atoms of the different constituents of the alloy at the sites of the crystal lattice. A weak point of the work is the absence of an allowance for the interaction among the external electrons themselves. For a quantitative refinement of the theory it is necessary to take this interaction into account.

The report by Prof. S. V. Vonsovskii, Candidates of Physico-Mathematical Sciences K. P. Rodionov and L. Ya. Kobelev, “Theory of the Hall Phenomenon in Ferromagnets,” was devoted to presenting the results of applying the same theoretical model of interacting external and internal electrons to explain the regularities of galvanomagnetic phenomena. If in this scheme the magnetic interaction is taken into account, then it can be easily shown that the change in electrical resistance upon magnetization of ferromagnets will be determined not by the external magnetic field but by the resulting magnetization of the body. A general method was also set forth for constructing and solving statistical kinetic equations for galvanomagnetic phenomena with allowance for magnetic interaction between electrons.

In the report by Candidate of Physico-Mathematical Sciences A. I. Rezanov, “Thermal and Thermoelectric Properties of Ferromagnetic Metals,” a calculation was presented, on the basis of a model of interacting external and internal electrons, of the thermal and thermoelectric properties of ferromagnets

near the Curie point. This calculation leads to characteristic “corrections” in the coefficients of thermal conductivity and thermoelectric effects that depend on the square of the spontaneous magnetization. The calculation of the coefficient of thermal conductivity and of the coefficient of sound attenuation in ferromagnets at low temperatures on the basis of the same theoretical scheme leads to additional terms in these coefficients with a special temperature dependence not characteristic of non-ferromagnetic metals.

The report by N. P. Patrakhin, “On the theory of galvanomagnetic and thermomagnetic phenomena in ferromagnets,” was devoted to presenting the results of applying the theory of interacting internal and external electrons to the explanation of special properties of these phenomena in ferromagnetic substances. It was shown that the Hall–Kikoin constant and the coefficients of thermomagnetic effects depend on the magnitude of the spontaneous magnetization, while the effects themselves are determined not by the external magnetic field but by the resultant magnetization of the body.

In the report by Prof. S. V. Vonsovskii and Candidate of Physical and Mathematical Sciences E. N. Agafonova, “On the theory of ferromagnetic semiconductors,” the foundations of a many-electron theory were set forth, in which the polar and excited states of electrons are taken into account. The results of the general theory may be applied to the explanation of the temperature dependence of the spontaneous magnetization of ferromagnetic semiconductors. The principal possibility was shown of the existence of ferromagnetic semiconductors possessing, in addition to the usual high-temperature Curie point, also a low-temperature one (in particular, at 0°K). In the study of the phenomenon of ferromagnetism of alloys in an exciton-polar model, a temperature dependence of the spontaneous magnetization of the alloy may be obtained at low temperatures (near 0°K) and at high temperatures (near the Curie point). It was shown that the Curie point of an alloy depends on the concentration of the components of the alloy, on the degree of short-range order in the arrangement of atoms at the sites of the crystal lattice of the alloy, and also on the integral of exchange with allowance for the excited states of the electrons.

In the report by Prof. S. V. Vonsovskii and Candidate of Physical and Mathematical Sciences A. V. Sokolov, “Quantum theory of the optical, magneto-optical, and photoelectric properties of ferromagnets,” an interpretation of all these phenomena was given on the basis of the already mentioned exchange model of external and internal electrons. It was shown that the optical characteristics—the absorption indices, the reflective and radiative abilities of ferromagnets both in the infrared and in the visible and ultraviolet regions of the spectrum—are functions of the spontaneous magnetization, which also explains all ferromagnetic anomalies of optical properties. It proved possible for the first time to show that the principal parameters of magneto-optical phenomena—the angle of rotation of the plane of polarization and the ellipticity of light in the Faraday and Kerr phenomena—are likewise proportional not to the magnetic field but to the magnitude of the resultant magnetization of the ferromagnet. The proportionality coefficients in the expressions for these quantities (the Shchegolev and Kerr constants), besides depending on frequency and temperature, are functions of the spontaneous magnetization. Functions of this same quantity are also the photoelectric current and the effective work function.

In the report by Prof. M. M. Noskov, “Some regularities in the magneto-optical properties of ferromagnets,” the results were presented of measurements of the temperature dependence of magneto-optical rotation in nickel, which indicate the presence of this rotation even at temperatures above the Curie point. Experiments on nickel–copper alloys showed that the Kerr constant depends quadratically on the spontaneous magnetization. The report also discussed the conclusions of the theory of Vonsovskii-

...Sokolov in the light of experimental data, and its validity was qualitatively demonstrated.

In the report by Prof. E. I. Kondorskii, “Single-domain structure and the theory of the magnetic properties of highly coercive ferromagnets,” a detailed survey was given of the author’s fundamental works in recent years on the theory of the technical magnetization curve of ferromagnetic materials. High values of coercive force, in the hundreds and thousands of oersteds, arise when the processes of boundary displacement between ferromagnetic regions are delayed or completely suppressed. The upper limit of the coercive force is determined by the ratio of the generalized constant of magnetic anisotropy to the saturation magnetization. Boundary-displacement processes are eliminated if the ferromagnetic material is broken up into separate regions isolated from one another in the magnetic sense. Therefore the determination of the conditions under which a “single-domain” or “single-region” structure arises coincides with the determination of the condition for obtaining an extremely high coercive force. The author subjected all previous attempts to determine these conditions to a profound critique. Proceeding from the conditions for a minimum of the total thermodynamic potential, the author obtained a formula for the critical dimensions of ferromagnetic specimens. It was shown that the magnetic field in the process of remagnetization can destroy a structure that had previously been single-domain. The limiting value of the coercive force is obtained only when the particles remain single-domain during the process of remagnetization. The author then derived new, more precise formulas for the average magnetic susceptibility of powders and for the effective demagnetizing factor of individual particles. It turns out that the concentration of a powder can change the conditions for the single-domain state of ferromagnetic particles.

In the report by Corresponding Member of the Academy of Sciences of the BSSR N. S. Akulov and G. S. Krinchik, “On the magnetic and mechanical properties of ferromagnets in the dynamic regime,” the results of extremely important and interesting work by the authors on magnetodynamics were presented, the foundations of which were created and developed by V. K. Arkad’ev and his school. In the first part of the report, a calculation was given of vortex microcurrents arising during the displacement of boundaries between ferromagnetic regions. In doing so the authors assume that, under the action of an external field, the structure of the regions changes in such a way that magnetically nonequilibrium layers arise, parallel to the external field, which determine the resultant magnetization of the specimen. The authors then consider the cases of weak and strong surface effect. In the first case they find formulas previously obtained by V. K. Arkad’ev. In the second case, formulas coinciding with those obtained earlier by K. M. Polivanov. It is significant that the decline of the magnetic permeability of ferromagnets throughout the entire frequency interval has the same physical nature and can be explained from a unified point of view. In the second part of the report it was shown that in ferromagnets, in addition to the losses caused by irreversible processes of boundary displacement between regions under alternating fields, there are energy losses due to reversible boundary displacements. If the first losses are proportional to the cube of the stress amplitude, then the second are proportional to the square of the amplitude, and the proportionality coefficient is a function of frequency. The difference of the dynamic value of the $\Delta E$ effect from its static value was shown. The frequency dependences obtained further agree well with experiment. In conclusion, the report gives general relations for the frequency dependence of changes in various properties of ferromagnets in the dynamic regime.

In the report by Prof. Ya. G. Dorfman, “On ferromagnetic and antiferromagnetic semiconductors as a problem of the physics of the solid state,” a critical review was given of contemporary views on the nature of ferrites. The speaker convincingly showed the necessity of a comprehensive study

of various physical properties of these extremely important magnetic materials. All existing attempts to explain their magnetic properties suffer from one-sidedness and require a radical reconsideration on the basis of comprehensive study. The author expresses an extremely interesting idea about the relation between the ferromagnetic and antiferromagnetic states in ferrites, whereby the problem of ferromagnetic and antiferromagnetic semiconductors and dielectrics acquires not narrowly “magnetic” interest, but represents a most important problem of solid-state physics as a whole.

The report by Full Member of the Academy of Sciences of the Ukrainian SSR B. G. Lazarev, Candidate of Physico-Mathematical Sciences B. I. Verkin, and Candidate of Physico-Mathematical Sciences N. S. Rudenko, “Magnetic properties of dia- and paramagnetic metals at low temperatures,” was devoted to an exposition of fundamental work on magnetism at low temperatures. The magnetic properties were investigated of the purest possible single crystals of bismuth, antimony, zinc, cadmium, beryllium, magnesium, tin, indium, and mercury in the temperature range from room temperature down to 1.5°K and in the field range from 1500 to 15000 oersteds. Universal laws of the dependence of the magnetic permeability of these metals on the magnetic field were discovered. Detailed studies were carried out of the anisotropy of the magnetic properties of a number of metals. The laws established are of enormous interest for all solid-state physics. This work is one of the chief achievements of Soviet solid-state physics in recent years and was awarded the Stalin Prize in 1951.

In the report by Prof. K. M. Polivanov, “Frequency characteristics of modern magnetic materials,” certain general questions of magnetodynamics were touched upon, the founder of which is V. K. Arkad’ev. The study of the frequency characteristics of various technical ferromagnetic materials shows that the decrease in magnetic permeability and the increase of losses in most cases cannot be explained by simply taking into account a single surface effect. To explain the frequency dependences it is necessary to take into account various external factors. Among these are processes leading to irreversible transitions, processes associated with the duration of establishment of an equilibrium state (relaxation processes), resonance phenomena of macroscopic and microscopic character observed at high frequencies, and also possible influences of structural inhomogeneity, likewise of macroscopic and microscopic character.

In the report by Doctor of Physico-Mathematical Sciences K. P. Belov, “Investigation of magnetoelastic phenomena in ferromagnetics in the region of the paraprocess,” experimental data were presented on magnetoelastic phenomena in the region of the paraprocess (magnetostriction, the influence of elastic stresses on the true magnetization and the Curie point). The dependence of magnetoelastic phenomena in the region of the paraprocess on temperature, elastic stresses, and the magnetic field was investigated. Ways were indicated for the practical use of the results of the investigation in order to improve the properties of alloys of the invar and elinvar type. An important conclusion of the author’s work is the connection established by him between the phenomena of the paraprocess and the dependence of the Curie point, and consequently also of the exchange energy, on interatomic distances in the crystal lattice of ferromagnetics.

In the report by Prof. E. I. Kondorskii and Senior Research Associate L. N. Fedotov, “Ferromagnetism of alloys at low temperatures,” general considerations were set forth regarding the importance for the entire theory of ferromagnetism as a whole of low-temperature measurements, as well as the results of the authors’ experiments on the study of the magnetic saturation of iron-nickel alloys in the range from nitrogen to hydrogen temperatures. It was established that the three-halves law is valid not only for pure metals, but also for iron-nickel alloys for all the studied con-

concentrations. The constant parameter in this law depends in a complicated way on the composition of the alloy, and there is no direct proportionality between this parameter and the Curie point. In the experiments it was established that the above-mentioned parameter and the value of the mean atomic moment of the alloy depend on the heat treatment of the alloys, which is the result of the influence of ordering processes. In the discussion of the report, an extensive discussion unfolded on questions of low-temperature experimental technique and on the field of applicability of the law of three seconds.

The report of Candidate of Physico-Mathematical Sciences I. M. Kirko, “On the Dispersion of Magnetic Permeability of Polycrystalline Ferromagnets in the Range of Audio Frequencies,” was devoted to the presentation of results of measuring the frequency dependence of the complex (in Arkad’ev’s sense) magnetic permeability of a substance in steels of various grades, as well as in 45% and molybdenum permalloys. The measurements confirmed the validity of the general relaxation law of variation of magnetic permeability in the range of audio frequencies. The regularities of the influence of a constant magnetizing field on the character of the dispersion of permeability were investigated. Much attention in the report was given to questions of measuring technique at high frequencies.

The report of Prof. Ya. S. Shur, “On the Magnetic Structure of Magnetically Textured High-Coercivity Alloys,” was devoted to a survey of contemporary ideas on the physical nature of hard magnetic materials. On the basis of a comprehensive study of the magnetic, magnetostrictive, electrical, galvanomagnetic, and other properties of magnetically textured high-coercivity alloys, it is possible to give a qualitative model of the magnetic structure of these materials; the principal features of this model are: single-domain character, the presence of interaction between magnetically separated regions, and the occurrence of processes of magnetization and remagnetization mainly by rotation of the vectors of spontaneous magnetization in isolated regions. A connection has been established between the magnetic texture and changes in the crystallographic structure of alloys.

In the report of Doctor of Physico-Mathematical Sciences R. V. Telesnin, “Some Regularities of Magnetic Viscosity,” a survey was given of the author’s very important investigations on magnetic viscosity. Determination of the relaxation times of the establishment of a new magnetic state after a change in the magnitude of the magnetic field in various materials and under various external conditions made it possible to establish the first rule of viscosity, according to which the relaxation time is proportional to the differential magnetic susceptibility and inversely proportional to the absolute temperature. Further, the author establishes a second rule of magnetic viscosity, according to which the relaxation time is determined only by the final state of the ferromagnet, if the change in field exceeds a certain value characteristic for each material. High-coercivity alloys possessing superviscosity do not obey the first rule.

The report of Candidate of Physico-Mathematical Sciences E. F. Kuritsina, “On the Temperature Dependence of Magnetic Viscosity,” was devoted to presenting the results of an investigation of the temperature dependence of magnetic viscosity of pure iron, cobalt, iron–nickel alloys, and nickel–zinc ferrites. In the alloys and ferrites deviations were found from the rules of magnetic viscosity established for pure ferromagnets by R. V. Telesnin.

In the report of Corresponding Member of the Academy of Sciences of the Turkmen SSR G. G. Ananaev, “Change in Electrical Resistivity in a Longitudinal Magnetic Field and the Thermomagnetic Effect of Iron–Platinum Alloys,” the results of investigations were presented, the principal task of which was to clarify the influence of ordering processes in iron–platinum alloys (for compositions close to 75 atomic percent iron) on galvanomagnetic effects.

The internal stresses arising upon ordering of an alloy change the magnitude of both the galvanomagnetic and the thermomagnetic effects.

The report of Candidate of Physico-Mathematical Sciences N. I. Erëmina, “Magnetic Metallography and Its Application,” was devoted to an exposition of the author’s work on applying the method of magnetic colloid figures to the study of the structure of ferromagnetic metallic alloys. On the basis of very rich illustrative material, the author convincingly showed the great practical value of this promising method, which in a number of cases can supplement, and in some cases also solve anew, problems of structural analysis inaccessible to ordinary methods of metallography. The report provoked a lively discussion.

In the report of Candidate of Physico-Mathematical Sciences N. N. Buinov, Candidate of Technical Sciences R. M. Lerman, and V. V. Kloshchina, “Electron-Microscopic Study of the Structure of an Alloy of Aluminum and Magnesium,” the results of the authors’ experiments on the study of the structure of high-coercivity alloys were presented. The investigations were carried out by the oxide-film method. The report was illustrated by numerous electron micrographs recording various structural states of the alloys. On the basis of an analysis of the micrographs, definite assumptions were put forward concerning the structure of the alloys in the high-coercivity state.

In the report of Prof. Ya. S. Shur, Candidate of Physico-Mathematical Sciences T. D. Zotova, V. A. Zaikova, and I. A. Chebotarëva, “On the Dependence of the Coercive Force on the Sizes of Powder Particles and on the Thickness of a Sheet of Soft Magnetic Materials,” experimental results of the authors were presented which show that in all the materials studied, beginning approximately with equal dimensions of the sheet thickness and the diameter of the powder particles, a sharp increase of the coercive force occurs, which compels one to assume a qualitative change in the magnetic structure of the materials, starting from certain small critical dimensions of ferromagnetic specimens.

The report of Senior Research Associate I. M. Puzey, “The Anisotropy Energy of Alloys of the Permalloy Class,” was devoted to an account of the results of measuring the constants of magnetic anisotropy of ternary permalloy alloys. The measurements were made on single-crystal specimens. The results of the author’s work showed the existence of a whole region of concentrations of these alloys where, with the aid of appropriate heat treatment (through ordering processes), materials of high permeability can be obtained. All those who spoke in the discussion of the report unanimously noted the very great significance of the work carried out by the author and emphasized the high experimental technique of its execution.

The report of Candidate of Physico-Mathematical Sciences N. V. Volkenshtein, “Study of the Relation between the Hall–Kikoin Constant of Ferromagnetic Alloys and Spontaneous Magnetization,” was devoted to an account of the results of investigations by A. P. Komar and the author of the Hall–Kikoin phenomenon in a ferromagnetic ordering alloy of the nickel–manganese system. These studies showed for the first time that the Kikoin constant is a function of spontaneous magnetization.

In the report of Candidate of Physico-Mathematical Sciences V. V. Parfenov and V. R. Abel’s, “Investigation of the Temperature Dependence of the Hall–Kikoin Effect in Electrolytic Iron,” the results of an experimental study were presented which showed that in iron the same regularities are fulfilled for the transverse odd galvanomagnetic effect as were established by I. K. Kikoin for nickel and by A. P. Komar and N. V. Volkenshtein for a nickel–manganese alloy.

The report of Prof. Ya. S. Shur and Candidate of Physico-Mathematical Sciences T. D. Zotova, “Investigation of the Phenomenon of the Change of Electrical Resistance in Magnetic

in the field in single crystals of transformer steel, was devoted to the results of an experimental investigation by the authors, which showed that the observed “anomaly” in transformer steel (the same sign of the longitudinal and transverse effects) is caused by a special relation between the anisotropy constants of the galvanomagnetic even effect, as was indicated by S. V. Vonsovskii on the basis of an analysis of the law of even effects. The work of S. Akulov, in methodological respect, is of great interest, since in it specimens of single crystals in the form of cylindrical rods were obtained for the first time by the method of spark machining.

In the reports of Candidate of Physico-Mathematical Sciences I. G. Fakidov and N. P. Grazhdankina, “Dependence of the Electrical Resistance of Ferromagnetic Chromium–Tellurium Alloys and Manganese–Surma on the Magnetic Field,” Candidate of Physico-Mathematical Sciences A. K. Kikoin, “Investigation of Ferromagnetic Chromium–Tellurium Alloys,” and F. S. Smirnov, “Investigation of Ferromagnetic Chromium–Sulfur Alloys,” the results were presented of experimental investigations of magnetic, thermal, and galvanomagnetic phenomena for ferromagnetic alloys of nonferromagnetic components. The results of these investigations are of interest for refining the criteria of the ferromagnetic state.

The reports of Senior Research Associate G. A. Smolenskii, “Nonmetallic Ferromagnets (Ferrites),” Candidate of Technical Sciences N. N. Shol’ts, “Ferromagnetic Ferrites,” and Candidate of Physico-Mathematical Sciences M. A. Grabovskii, “Some Physical Properties of Magnetites,” were devoted to the presentation of physicochemical, electrotechnical, and technological investigations of semiconductor ferromagnetic materials—ferrites or oxyphers. Discussion of the reports showed enormous interest in these materials, which have unusually broad prospects for practical application.

The report of Candidate of Physico-Mathematical Sciences F. M. Gal’perin, “Atomic Magnetic Moments and Crystal Structures of Ferromagnetic Metals and Alloys,” was devoted to a presentation of the author’s work in which he attempted to establish a regular connection between the magnitude of the average atomic magnetic moments and the geometry of the crystal lattice and the physical properties of atoms of metals or alloy components. A number of the author’s propositions were subjected to sharp criticism by those who spoke in the discussion (Prof. Ya. G. Dorfman, B. I. Verkin, and others). The greatest objections were aroused by the author’s attempts to justify theoretically the formulas he proposed on the basis of Lande’s scheme, which is far from real validity, and of Sleater’s concepts concerning the structure of the electron shells of isolated atoms.

In the report of Candidate of Physico-Mathematical Sciences F. M. Gal’perin and Candidate of Physico-Mathematical Sciences T. M. Perekalina, “Investigation of the Gyromagnetic Effect in a Chromium–Tellurium Alloy by the Classical Resonance Method,” the results were presented of measurements of the magnetomechanical ratio, carried out for the first time in the Soviet Union for a ferromagnetic material. The experiments showed that in the alloy under study the magnetomechanical ratio differs noticeably from its value for the free electron spin. This indicates that in the given alloy, apparently, orbital moments of the electrons play a large role. The report provoked a lively discussion on questions of experimental technique, accuracy of measurements, etc.

The report of Candidate of Technical Sciences B. M. Fradkin, “Calculation of the Electromagnetic Properties of Magnetodielectrics Associated with the Insulating Medium of Ferromagnetic Powders,” was devoted to a presentation of the author’s formulas for magnetic permeability and losses in magnetodielectrics. The work gives the most accurate calculation, which agrees sufficiently well with experimental data.

The reports by Candidate of Physico-Mathematical Sciences B. M. Kozyrev, “Resonance Paramagnetic Absorption in Liquid Solutions,” Candidate of Physico-Mathematical Sciences S. G. Salikhov, “Experimental Investigation of the Resonance Absorption of Certain Paramagnetic and Ferromagnetic Metals,” A. I. Rivkind, “Absolute Measurements of Paramagnetic Absorption in Perpendicular Fields at a Frequency of an Alternating Magnetic Field of \(10^7\) cycles,” and G. Ya. Glebashov, “On the Form of the Curves of Resonance Paramagnetic Absorption,” were devoted mainly to questions of paramagnetism in high-frequency fields. The reports presented the results of experimental and theoretical investigations by the authors, chiefly on paramagnetic resonance. In B. M. Kozyrev’s report, results were set forth for determining the dependence of the width of resonance curves on the concentration of magnetic ions at various frequencies of the alternating magnetic field. The question of the symmetry of the electric field in solutions of different concentration, the change in the form of the resonance curve under the influence of nuclear spin, and the regularities of resonance absorption in solutions with two magnetic constituents were considered. In S. G. Salikhov’s report, the author’s measurements on paramagnetic resonance in transition-group metals were presented. The influence of temperature, the dependence on the frequency of the alternating field, the gyromagnetic ratio, and the width of the resonance lines were investigated. Ferromagnetic resonance was investigated in the frequency interval from \(10^8\) to \(10^9\) cycles in powders and thin plates. The dependence of the effect on the direction of rolling in sheets was investigated. A. I. Rivkind’s report was devoted to the presentation of the method and results of absolute measurements of paramagnetic absorption in compounds of certain elements of the iron, platinum, and rare-earth groups, and a comparison with theory was also made. In G. Ya. Glebashov’s report, results of a theoretical calculation of the paramagnetic-resonance absorption curve with allowance for higher approximations were presented. All these reports evoked lively debates; questions concerning the methodology of high-frequency measurements were subjected to especially detailed discussion.

A. S. Borovik-Romanov’s report, “The Magnetic Susceptibility of Solid Oxygen,” was devoted to measurements of the temperature course of the magnetic susceptibility in the region of hydrogen and helium temperatures. The author developed a special high-sensitivity circuit for ballistic measurements, as well as a method for obtaining homogeneous samples of solid oxygen. The magnetic susceptibility falls by \(9\%\) in the interval from 20 to 14°K, while in the region of helium temperatures it exhibits only a very weak linear increase. The results obtained confirm the conclusions of the theory of Landau and Pomeranchuk.

In the report by Prof. R. I. Yanus and Candidate of Physico-Mathematical Sciences V. I. Drozhzhina, “On the Relation between the Rotational and Commutational Hysteresis of Dynamo Steel,” the authors’ measurements carried out on disks (diameter 240 mm and thickness 0.5 mm) after different heat treatments and degrees of cold working were presented. The experiments showed that the ratio of rotational hysteresis to commutational hysteresis varies from specimen to specimen and depends on the degree of cold working. With an increase of the latter, commutational hysteresis increases more rapidly than rotational hysteresis, and the difference in the rate of growth is the greater, the softer the specimen.

In the report by Docent P. S. Sarapkin, “Hysteresis Losses in Strong Rotating Magnetic Fields,” it was shown, on the basis of the author’s measurements, that the losses due to rotational hysteresis differ from zero even at field values close to saturating and exceeding them. For the measurements the author used the method of automatic photographic recording.

N. I. Vtyurin’s report, “Temperature Dependence of Hysteresis Losses in Rotating Magnetic Fields,” was devoted to the results of the author’s investigation in fields up to 12,000 oersteds on monocrystalline

nickel sphere. The results of the observations on the whole confirm the theory of N. S. Akulov.

The reports by Candidate of Physical and Mathematical Sciences V. F. Ivlev, “The Influence of Elastic Stresses on Irreversible Jumps of Magnetization,” and “Temperature Dependence of Irreversible Jumps of Remagnetization,” were devoted to an exposition of the author’s experimental work. With an increase in load, the number of jumps in nickel decreases and tends to zero when the curve degenerates into a straight line (pure rotation processes). As the load increases, the maximum in the number of jumps shifts toward stronger fields. With increasing temperature the number of jumps, as well as their magnitude, decreases according to an exponential law. A rise in temperature leads to a narrowing of the field interval in which irreversible processes of displacement of the boundaries between ferromagnetic regions occur, and to their displacement into the region of weaker fields.

In the report by Prof. B. F. Tsomakion and Candidate of Physical and Mathematical Sciences V. F. Ivlev, “Methods for Investigating Irreversible Jumps of Remagnetization,” a description was given of an original automatic method for counting and photographic recording of jumps of irreversible remagnetization under pulsed variation of the strength of a constant magnetizing current.

The report by Prof. K. M. Polivanov and V. V. Kuznetsky, “Pulse Magnetization of Permanent Magnets,” was devoted to presenting the results of the authors’ investigation, which clarified the dynamics of the processes of magnetization of high-coercivity alloys, established the necessary values of field strength, pulse duration, the required number of repeated pulses, and also a number of special changes in the magnetization of magnets after repeated pulses.

In the report by Candidates of Physical and Mathematical Sciences N. I. Eremina and G. S. Krinchik, “The Influence of Elastic Stresses on the Processes of Displacement of the Boundaries of Ferromagnetic Regions,” experimental results were set forth on the study of changes in the magnetization of ferromagnets under the combined and combined action of a magnetic field and elastic tensile strains by means of a magnetometric method of measurement. In this, the authors, in contrast to results obtained by the commutation method, discovered an effect of decrease of magnetization upon removal of the load. The work also investigated the metastability of states of a ferromagnetic structure under application of external stresses in a weak constant field by action of an alternating field with amplitude decreasing to zero. The report aroused lively debate. The desirability was indicated of comparing the results of this interesting investigation with data on measuring magnetostriction under the same conditions.

The report by D. D. Mishin, “The Influence of Small Elastic Stresses on the Initial Susceptibility of a Ferromagnet,” was devoted to questions of the dependence of the reversible susceptibility of soft ferromagnetic materials on small elastic deformations for different magnetic and crystallographic textures. The measurement results confirm the theoretical predictions (Vonsovsky).

In the report by Candidate of Physical and Mathematical Sciences D. A. Finger, “The Influence of Alternating Loads on the Magnetic Properties of Ferromagnets,” the fundamental difference was noted between the influence of constant and sign-alternating loading on the magnetization curves of ferromagnets. Pulsating loads always lead to an increase in magnetization, the greater the greater the role played in the processes of displacement of the boundaries between ferromagnetic regions by inhomogeneities of internal stresses. The results obtained confirm E. I. Kondorsky’s theory of the relation of the magnetization of rocks to seismic and tectonic phenomena.

The report by Candidate of Physical and Mathematical Sciences A. A. Lukshina, “Dependence of the Effect of Thermomagnetic Treatment on the Initial Properties of Ferromagnetics,” was devoted to the investigation of alnico alloys and 65 permalloy.

with different initial magnetic properties. The experiments showed that the relative magnitude of the effect produced by thermomagnetic treatment increases with improvement in the initial magnetic properties of the material.

The report by Prof. Ya. S. Shur and F. N. Dunaeva, “The dependence of the effect of thermomechanical treatment of soft magnetic materials on the magnitude of the load and the temperature of this treatment,” dealt with the results of studying this treatment in specimens of transformer steel and 65 permalloy. The authors showed the existence of a “critical” load and an “optimal” temperature at which the greatest increase in maximum permeability and the greatest decrease in coercive force and saturation magnetostriction occur. The effect is absent when the load is applied and removed at temperatures above the Curie point. Plastic deformations always destroy the magnetic texture. It is suggested that the principal cause of the effect is a redistribution of internal stresses.

In the report by Candidate of Physico-Mathematical Sciences E. P. Svirina, “The influence of the degree of order on the magnetic properties of highly ordered alloys,” the author presented the results of experimental investigations of changes in magnetic properties during superstructural transformations in toroidal specimens of molybdenum permalloy. The experimental results are analyzed on the basis of N. S. Akulov’s theory.

The report by K. M. Bolshova, “Investigation of magnetization in heterogeneous and stressed alloys based on iron in strong fields,” concerned the study of the law of approach to saturation in the iron—molybdenum, iron—tungsten, and iron—copper alloy systems. In the homogeneous region, N. S. Akulov’s law of approach to saturation is valid. In heterogeneous materials there are deviations from this law; an additional term appears, the coefficient of which the author calls magnetic stiffness. Magnetic stiffness depends on the total volume of inclusions, and the temperature dependence in the region of low temperatures is very weak. The results of the work are important for the theory of heterogeneous and stressed ferromagnetic materials. The report gave rise to considerable discussion in connection with the theoretical interpretation of the measurement results.

In the report by Candidate of Physico-Mathematical Sciences V. V. Parfenov, “Investigation of the magnetic permeability of ferromagnets in the region of high magnetic fields,” the author presented the results of his measurements of magnetization curves for a large number of ferromagnetic materials (permalloy, alsifer, high-coercivity alloys, etc.) in fields up to 12,000 oersteds. The experiments showed that, in the region of very high fields, there is a deviation from the law of approach to saturation of N. S. Akulov.

In a second report by the same author, “On the use of electromagnets for ballistic measurements by the switching method,” it was shown, on the basis of measurements performed, that despite long relaxation times, electromagnets can be used for the aforementioned ballistic method.

The reports by Prof. R. I. Yanus, Candidate of Physico-Mathematical Sciences V. I. Drozhzhina, and E. F. Shabalina, “A differential-pulse method of measurements carried out by means of a ballistic galvanometer” and “On the hysteresis of the demagnetization coefficients of ferromagnetic rods,” dealt with very important and subtle questions of the theory and practice of magnetic measurements. The authors’ theoretical study disclosed experimentally the hysteresis of the ballistic demagnetizing factor, failure to take account of which can introduce large errors into measurements. The differential-pulse method developed by the authors can, in a number of cases when recording magnetic hysteresis loops, give higher accuracy than the “ordinary” method.

In the reports by A. Ya. Vlasov, “Investigation of the Temperature Dependence of Nickel Magnetostriction by the Method of Automatic Photographic Recording” and “The Influence of the Method of Demagnetization on the Magnitude of the Observed Magnetostriction,” results were presented of measurements of the temperature behavior of magnetostriction in the interval from \(-183^\circ\mathrm{C}\) to \(+384^\circ\mathrm{C}\), as well as of the behavior of magnetostriction when samples were demagnetized by heating to a temperature above the Curie point, by demagnetization by switching on a solenoid current, and also by commutation followed by demagnetization with an alternating current of decreasing amplitude.

In the report by Candidate of Physical and Mathematical Sciences M. V. Dekhtyar, “On a Magnetic-Hysteresis Loop Close in Shape to a Rectangle,” a new method was presented for obtaining such loops in samples of a two-phase iron–nickel alloy (with 65% nickel), deformed in the recrystallization-temperature interval, as well as in a single-phase alloy—doped permalloy. A discussion followed the report; in particular, the question of a quantitative characterization of the degree of “rectangularity” of the loop was discussed.

In the report by V. V. Druzhinin, “On the Anisotropy of Magnetic Susceptibility and Coercive Force in Single Crystals of an Iron–Silicon Alloy,” the author’s measurements in the study of this anisotropy on samples in the form of single-crystal disks were presented. The investigation showed that in weak fields there is disagreement with Williams’s data for single-crystal frames, namely, the direction with “minimum permeability and maximum coercive force” is not trigonal, but diagonal.

The report by Prof. Ya. S. Shur, Candidate of Physical and Mathematical Sciences V. I. Drozhzhina, and M. G. Luzhinskaya, “Electrical Resistance and the Phenomenon of Change of Electrical Resistance in the Magnetic Field of a Magnico Alloy,” was devoted to the presentation of the results of measurements of these quantities in samples in various magnetically textured states. The experiments showed that, as a result of thermomagnetic treatment, anisotropy of electrical conductivity arises in the alloy. This indicates that thermomagnetic treatment leads not only to the creation of a magnetic texture in the alloy, but also to a texture in the structural arrangement of the material. The results of this work shed light on the nature of the physical processes occurring during thermomagnetic treatment of ferromagnetic materials.

In the report by Prof. Ya. S. Shur and Candidate of Physical and Mathematical Sciences T. D. Zotova, “On the Dependence of the Coercive Force of Powders of High-Coercivity Alloys on Particle Size,” the results of the authors’ investigation were presented, aimed at clarifying the reason why, in an alloy of the alnico type, a decrease in the particle size of the powder was accompanied only by a decrease in coercive force. The authors showed that the coercive force remains constant (down to particle sizes of \(25\) microns) if already prepared, i.e., deformed, particles subjected to heat treatment including heating to the temperature of the single-phase state are used, and, consequently, the coercive force is measured on undeformed particles. The decrease in coercive force observed earlier is caused by the influence of work hardening on the processes of decomposition of the initial phase.

The report by Candidate of Sciences D. A. Shturkin, “Magnetostriction of High-Coercivity Alloys,” concerned the author’s experimental investigations of the temperature dependence of the curves and hysteresis loops of magnetostriction of high-coercivity alnico and vicalloy materials possessing magnetic texture. It was established that, depending on the magnetic texture, a different temperature behavior of the curves and hysteresis loops of magnetostriction is observed. The observed regularities can be qualitatively explained if it is assumed that the magnetic structure of these alloys has a single-domain character.

The report by Prof. Ya. S. Shur, N. A. Baranova, and V. A. Zaikova, “Temperature Magnetic Hysteresis of Highly Coercive Alloys,” was devoted to the exposition of studies of this phenomenon in an alloy of the alniko type, subjected to various treatments that create different magnetically textured states in the material. The results obtained—the presence of temperature magnetic hysteresis and its dependence on the degree of magnetic texture—lead one to suppose that in the alloy the magnetic structure is not completely single-domain: in a certain volume of the material there exist groups consisting of a small number of regions in which (groups) processes of boundary displacement may occur.

The conference adopted a resolution summing up the results of work on the physics of magnetic phenomena carried out in the USSR in recent years; it noted the great successes achieved in the development of the study of magnetism, in the creation of new instruments and apparatus, and in the introduction of the work of Soviet magnetologists into our socialist industry. The successes achieved are determined to a considerable extent by the creative growth and expansion of the cadre of physicist-magnetologists.

At the same time, the Conference also noted numerous shortcomings that still exist in the work of Soviet physicist-magnetologists. A number of important problems of magnetism are not being developed at all; coordination of the work of different groups of physicist-magnetologists is weak; the connection among physicists, metallurgists, and electrical engineers engaged in practical problems of magnetism is insufficient. The Conference noted a number of shortcomings in the training of specialist physicist-magnetologists, as well as in publishing work and in the absence of critical and discussion papers on questions of magnetism.

The Conference outlined the main paths for the development of the physics of magnetic phenomena in the coming years.

S. V. Vonsovskii.