Lev Davidovich Landau (22.01.1908-1.04.1968) was a Soviet theoretical physicist and an academician (1946). He was born in Baku. He graduated from Leningrad University (1927). In 1927-32 he was a postgraduate student and then a research fellow at the Leningrad Physico-Technical Institute. In 1932—37 he was head of the theoretical department of the Kharkov Physico-Technical Institute and at the same time head of the department of theoretical physics at the Kharkov Institute of Mechanics and Machine Building, and from 1935 of the department of general physics at Kharkov University. From 1937 he was head of the theoretical department of the Institute of Physical Problems of the USSR Academy of Sciences. At the same time he was professor at Moscow University (1943—47 and from 1955) and at the Moscow Institute of Physics and Technology (1947-50).
His research concerned quantum mechanics, solid-state physics, the theory of second-order phase transitions, the theory of the Fermi liquid and the theory of the superfluid liquid, the physics of cosmic rays, hydrodynamics, physical kinetics, quantum field theory, the physics of elementary particles and plasma physics.
He was the first to obtain (1937) the relation between the density of levels in a nucleus and the excitation energy, and along with H. Bethe and V. Weisskopf he is one of the originators of the statistical theory of the nucleus. In 1957 he proposed the law of conservation of combined parity (it was formulated at the same time by A. Salam, T. Lee and C. Yang), and independently of the same scientists he put forward the theory of the two-component neutrino. Research on the theory of phase transitions occupies an exceptional place in Landau's scientific work. He studied second-order phase transitions in detail and created their theory (1935 — 37). In the spirit of the ideas of the theory of phase transitions Landau (together with V. L. Ginzburg) constructed in 1950 a phenomenological theory of superconductivity, which made it possible to explain a number of essential properties of superconductors and later became the basis for the creation of the theory of type II superconductors and the theory of superconducting alloys (the Ginzburg–Landau–Abrikosov–Gorkov theory).
In 1940—41 he created the theory of the superfluidity of helium II, which explained all the properties of it then known and predicted a number of new phenomena, in particular the existence of second sound in helium. This research laid the foundation of the physics of quantum liquids. In 1956 Landau developed the theory of such liquids (the theory of the Fermi liquid). In 1962 Landau was awarded the Nobel Prize for pioneering research on the theory of condensed matter and especially of liquid helium.
In 1930 he worked out the theory of the diamagnetism of free electrons (Landau diamagnetism), explaining for the first time the nature of the diamagnetism of metals. In 1933 he introduced the concept of antiferromagnetism as a particular phase of a magnetic material. In 1935, together with E. M. Lifshitz, he worked out the theory of the domain structure of ferromagnets and established the equation of motion of the magnetic moment (the Landau–Lifshitz equation).
Landau also achieved substantial results in hydrodynamics, physical kinetics and plasma physics. In 1936 he gave the kinetic equation for a plasma in the case of Coulomb interaction and established the form of the collision integral for charged particles.
A significant place in Landau's legacy belongs to the widely known multi-volume “Course of Theoretical Physics” which he created together with E. M. Lifshitz, which has been reissued in many languages of the world and has played a large part both in the development of theoretical physics itself and in the training of young theoreticians (Lenin Prize, 1962).
Hero of Socialist Labour (1954), USSR State Prizes (1946, 1949, 1953). A member of many foreign academies of sciences and scientific societies. The F. London Medal. He created a large school of theoreticians (I. Ya. Pomeranchuk, E. M. Lifshitz, I. M. Lifshitz, A. A. Abrikosov, A. B. Migdal, A. I. Akhiezer, L. P. Gorkov, V. N. Gribov, I. E. Dzyaloshinskii, L. P. Pitaevskii, I. M. Khalatnikov, V. B. Berestetskii, A. S. Kompaneets, Ya. A. Smorodinsky and others).