Dorfman, Yakov Grigoryevich (7.04.1898–5.02.1974) was a Soviet physicist and a doctor of physical and mathematical sciences (1934). Born in St Petersburg. Graduated from the Leningrad Polytechnic Institute (1925). In 1921–31 he worked at the Leningrad Physico-Technical Institute, in 1932–38 at the Urals Physico-Technical Institute, in 1938–44 he was head of the physics sector of the Azerbaijan Branch of the USSR Academy of Sciences, in 1945–58 he was at the Leningrad Hydrometeorological Institute, in 1958–64 at the All-Union Institute of Scientific and Technical Information, and from 1965 head of the sector for the history of physics at the Institute of the History of Science and Technology of the USSR Academy of Sciences.
His research was in the field of solid-state physics, magnetism and the history of physics. He put forward (1923) the idea of electron paramagnetic resonance and proved experimentally (1927) that the internal magnetic field present in ferromagnets is of non-magnetic origin. In 1930, together with I. K. Kikoin, he predicted a change in the contact potential of a ferromagnet in a magnetic field, and with Ya. I. Frenkel he constructed the theory of domain structure. He was the first to study (1933) the question of the magnitude of the magnetic moment in ferromagnetic alloys, treating the d electrons as the main carriers of the magnetic moment and the s conduction electrons as the main carriers of the chemical bond. In 1951 he predicted diamagnetic cyclotron resonance in semiconductors. He was the author of the two-volume “World History of Physics”.