When was the  Soviet, Russian and American theoretical physicist died who describe the magnetic phase diagram of type-II superconductors of Onsager?
Quantum vortex In physics, a quantum vortex represents a quantized flux circulation of some physical quantity. In most cases quantum vortices are a type of topological defect exhibited in superfluids and superconductors. The existence of quantum vortices was predicted by Lars Onsager in 1947 in connection with superfluid helium. Onsager also pointed out that quantum vortices describe the circulation of superfluid and conjectured that their excitations are responsible for superfluid phase transitions. These ideas of Onsager were further developed by Richard Feynman in 1955 and in 1957 were applied to describe the magnetic phase diagram of type-II superconductors by Alexei Alexeyevich Abrikosov. In 1935 Fritz London published a very closely related work on magnetic flux quantization in superconductors. London's fluxoid can also be viewed as a quantum vortex.
Aleksandr Chudakov Aleksandr Evgenievich Chudakov (16 June 1921 – 25 January 2001, Moscow) was a Soviet Russian physicist in the field of cosmic-ray physics, known for "Chudakov Effect", the effect of decreasing ionization losses for narrow electron-positron pairs and for experimentally confirming existence of the transition radiation.