Superconductor

36
Superconductor
Yu.N.Ryabinin left UPhTI because of the conflict with L.V.Shubnikov and L.D.Landau.
G.D.Shepelev who defended the first doctoral dissertation at Shubnikov’s Cryo Lab
(Shepelev, 1938) was placed at the head of this Lab. (Fig. 22). Then the Second World War
broke out and interests of the scientists shifted en masse in other directions. After
Germany’s aggression against the USSR Shepelev volunteered to the front and was killed in
action during the defense of Sevastopol at the age of 36.
Fig. 22. G.D.Shepelev at the helium liquefier (Cryogenic Laboratory UPhTI, 1932) and the
document about his defence (in 1938) of the Thesis “Magnetic Properties of
Superconducting Alloys”.
The very first reference to the research by Shubnikov, Khotkevich, Shepelev, Ryabinin
(Shubnikov et al., 1937), acknowledging it as a pioneering one, was made in the paper written
by A.A.Abrikosov (Abrikosov, 1957) which was published 20 years later. The author, acting on
the basis of the experimental results by Shubnikov, Khotkevich, Shepelev, Ryabinin
(Shubnikov et al., 1937) and the Ginzburg-Landau theory (Ginzburg & Landau, 1950;
Ginzburg, 1955), constructed the Type II Superconductor Theory which now could describe,
even quantitatively, these experimental results. It turned out that the thermodynamic critical
field Нc was roughly equal to the geometric average of the fields Нс1 and Нс2:
H
H
c c2
≈ ≈ 2 ⋅ æ
Hc H
1 c
Thus, the greater was the value æ, the smaller became Нc1 and the greater became Нс2, which
corresponded to Shubnikov and colleagues’ experimental results (Schubnikow et al., 1936;