LIFSHITS, IL’IA MIKHAILOVICH

(b. Kharkov, Russia, 13 January 1917; d. Moscow, U.S.S.R., 23 October 1982)

Physics.

Lifshits’ father, Mikhail Il’ich Lifshits, was a physician and a professor at the Kharkov Medical Institute; his mother, Bertha Evsorovna, was a houeswife. In his youth Il’ia was gratly influenced by his elder brother Evgenii, who also became a physicist.

Most of Lifshits’ life was associated with Kharkov. After graduating from the university there in 1936, he started to work in the theoretical department founded by Law Davidovich Landau at the Ukrainian Physico-Technical Institute. In 1939 Lifshits defended his candidate thesis, and in 1941 his doctoral dissertation, both of which dealt with the quantum mechanics of the condensed state. Then, at the age of twenty-four, he became the head of one of the two throretical groups at the Ukrainian Physico Technical Institute (the other one was headed by A. I. Akhiezer).

In the vast range of Lifshits’ research interests, the leading place belonged to solid state physics. He was also involved in various applied problems, however, including the theory of diffusion pumps, zone-refining of metals, and the physics of powder sintering. Soon after he had joined the Ukrainian institute, Lifshits had a short, unsuccessful period of experimental work at I. V. Obreimov’s laboratory. For most of his professional life, however, he was a “pure” theoretician with a fine physical sense who was able to uncover physics in many applied problems arising in engineering and technology.

The first, prewar series of Lifshits’ works was associated with the scattering of X rays by crystals. In this theory he took into account the presence of isotopes, of holes, and of other defects Characteristic of real crystals. He worked out a matrix method of analysis of phenomena associated with oscillations of the crystal lattice that enabled him to investigate the phonon spectrum.

In the late 1920’s Felix Bloch and Archibald Wilson demonstrated the fundamental importance of the structure of the energy spectrum of crystals for the description of their various properties. The states of electrons whose energy is close to the Fermi energy are crucial for the properties of metals, Lifshits stated and completely solved an important problem of reconstruction (reproduction) of the energy spectrum from the experimental data. The characteristic of the nonelastic scattering of neutrons, together with the resonance experiments, enabled Lifshits to reconstrust the Bose branch of the energy spectrum, and the effects observed in the presence of a magnetic field (for instance, the de Haas–van Alfven effect or that of de Haas–Shubnikow) made it possible for him to restore the Fermi branches. Combined efforts of Soviet theoreticians (most of them belonging to Lifshits’ school) and experimentalists have led to the determination of the topology of the Fermi surfaces practically for all metals. The shape of these surfaces has turned out to be fairly fantastic for a number of metals, and therefore they began to be called “monstres.”

Lifshits obtained important results related to the energy spectrum and quantum excitation of disordered media (amorphous bodies, disordered alloys). He made a great contribution to the formation of the notion of quantum crystals and studied the singularities of behavior of defects within this type of crystal. Lifshits also described these defects in terms of the quasiparticles able to move at absolute zero. With A. F. Andreev, Lifshits predicted the phenomenon of quantum diffusion in such crystals (which is something like tunneling through the interlattice barriers).

The physics of quasiparticles, founded in the Soviet Union by I. E. Tamm, Ia. I. Frenkel, L. D. Landau, S. I. Pekar, and others, was significantly enriched by Lifshits’ investigations.

The following series of Lifshits’ papers is related to the theory of phase transitions. He introduced a phase transition associated with reconstruction of the Fermi surface (the so-called 2 1/2 or Lifshits transition). He also described in detail the kinetics of the second-order phase transition and the transition from a superconducting to an ordinary state under the influence of a magnetic field. These results were complemented by investigations of phase transformation of macromolecules, which is a subject equally relevant for physicists, chemists, and biologists. Lifshits and his collaborators formulated the criteria for that type of transformation and built up their quantitative theory for single-chain molecules. These problems attracted Lifshits’ attention during the last years of his life.

The scientific activity of Lifshits received a wide recognition. In 1948 he was elected corresponding member, and in 1967 full member, of the Ukrainian Academy of Sciences; the Soviet Academy also elected him corresponding (1960) and full (1970) member. The leading position of Lifshits in Soviet physics was confirmed when he was invited in 1969 by P. L. Kapitsa to head the theoretical department at the Institute of Physical Problems in Moscow (a position earlier occupied by Landau). In 1967 Lifshits was awarded the Lenin Prize.

Lifshits suffered from heart disease and died after a short period of illness, as the result of a second heart attack. He was, however, active in science and teaching until the last weeks of his life.

BIBLIOGRAPHY

I. Original Works. A bibliography is in M. Ia. Azbel and M. I. Kaganov, “Ilia Mikhailovich Lifshits,” in Us pekhi fizicheskikh nauk, 91, no. 3 (1967), 560–561. Selected works are “Optical Behaviour of Non-ideal Crystal Lattices in the Infra-red,” in Journal of Physics (USSR), 7, no. 5 (1943), 215–228, no. 6 (1943), 249–251, and 8, no.2 (1944), 89–105; “O vyrozhdennykh reguliarnykh vozmushcheniiakh” (On degenerate regular perturbations), in Zhurnal eksperimentalnoi i teoreticheskoi fiziki, 17, no. 11 (1947), 1017–1025, and no. 12 (1947), 1076–1089; “Some Considerations on the Twinning of Calcite Crystals,” in Journal of Physics (USSR), 11, no. 2 (1947), 121–130, written with V. I. Obreimov; “Ob opredelenii energeticheskogo spektra boze-sistemy po ee teploemkosti” (On the determination of the Bose-system spectrum on the basis of its heat capacity), in Zhurnal eksperimentalnoi i teoreticheskoi fiziki, 26, no. 5 (1954), 551–556; “Ob opredelenii poverkhnosti Fermi i skorostei v metalle po ostsilliatsii magnitnoi vospriimchivosti metallow pri nizkikh temperaturakh” (On the determination of Fermi surface and of a metal on the basis of magnetic susceptibility oscillations at low temperatures), in Doklady Akademii nauk SSSR, 96, no. 1 (1954), 6, written with A. V. Pogorelov; “O structure energeticheskogo spektra i kvantovykh sostoianiiakh neuporiadochennykh kondensirovsnnukh system” (On the structure of an energetical spectrum and on quantum states, of disordered condensed systems), in Uspekhe Fizicheskikh nauk, 83, no.4 (1964), 617–663; “Elektronnaia teoriia metallov i geometriia” (Electron theory of metals and geometry), ibid., 129, no.3 (1979), 487-529, written with M. I. Kaganov; Elektronnaia teoriia metallov (Moscow, 1971), written with M. Ia. Azbel and M. I. Kaganov, translated by Albin Tubulewicaz as Electron Theory of Metals (New York, 1973); Kvaxichastitsy (Moscow, 1976), written with M. I. Kaganov; Elektronnaia teoriia metallov (Moscow, 1971), written with M. Ia. Azbel and M. I. Kaganov, translated by Albin Tubulewicz as Electron theory of Metals (New York, 1973); Kvazichastitsy (Moscow, 1976), written with M. I. Kaganov, translated by V. Kissin as Quasiparticles (Moscow, 1979); and Vvedenie v teoriia neuporiadochennykh system (Introduction to the theory of disordered systems; Moscow, 1982), written with S. A. Gredeskul and L. A. Pastur.

II. Secondary Literature. M. Ia. Azbel and M. I. Kaganov, “Ilia Mikhailovich Lifshits: K piatidesiatiletiiu so dnia rozhdenia” (For his fiftieth birthday), in Uspekhi fizicheskikh nauk, 91, no. 3 (1967), 559–561. Obituaries are ibid., 140 no. 3 (1983), 521–522; and in Physics Today, no. 3 (1983), 83–84.

V. J. Frenkel