Alexander Iosifovich Shalnikov (born 10.05.1905) — Soviet experimental physicist, academician (1979, corresponding member 1946). Born in Petersburg. Graduated from the Leningrad Polytechnic Institute (1928) and worked at the Leningrad Physico-Technical Institute. From 1935 he was at the Institute of Physical Problems of the USSR Academy of Sciences, in whose organisation he took an active part, and from 1938 was also a professor at Moscow University.
His main research was in physical chemistry, low-temperature physics and scientific instrument making. He developed methods of obtaining atomically dispersed mixtures and colloidal solutions of alkali metals in organic liquids, and created and improved a number of physical instruments (light-quantum counters, iconoscopes, electron diffraction cameras).
In the 1940s—50s he studied the intermediate state of superconductors and the properties of thin superconducting films. He detected a sharp rise in the critical fields of films in comparison with bulk superconductors and a substantial rise in the critical temperature for films condensed on a surface cooled to helium temperatures. He was the first to obtain (1941) reliable evidence of the two-phase nature of the intermediate state of superconductors.
He carried out a series of studies of the properties of liquid and solid helium. His research in recent years concerned the physics of quantum crystals, in particular the properties of crystalline helium. He developed a method of growing highly perfect single crystals of helium and was the first to obtain crystals in which quantum phenomena were detected — Poiseuille flow of a phonon gas and vacancy motion of charge carriers — and studied the thermal and mechanical properties of these crystals.
Three times a laureate of the State Prizes of the USSR (1948, 1949, 1953). The P. N. Lebedev Prize (1972).