SUPERCONDUCTIVITY: FROM ELECTRON INTERACTION TO NUCLEAR SUPERFLUIDITY

2010 ◽  
Vol 24 (20n21) ◽  
pp. 3814-3834
Author(s):  
David Pines

I present an expanded version of a talk given at the Urbana symposium that celebrated the fiftieth anniversary of the publication of the microscopic theory of superconductivity by Bardeen, Cooper, and Schrieffer — BCS. I recall at some length, the work with my Ph.D. mentor, David Bohm, and my postdoctoral mentor, John Bardeen, on electron interaction in metals during the period 1948–55 that helped pave the way for BCS, describe the immediate impact of BCS on a small segment of the Princeton physics community in the early spring of 1957, and discuss the extent to which the Bardeen–Pines–Frohlich effective electron-electron interaction provided a criterion for superconductivity in the periodic system. I describe my lectures on BCS at Niels Bohr's Institute of Theoretical Physics in June 1957 that led to the proposal of nuclear superfluidity, discuss nuclear and cosmic superfluids briefly, and close with a tribute to John Bardeen, whose birth centennial we celebrated in 2008, and who was my mentor, close colleague, and dear friend.

2020 ◽  
Vol 65 (1) ◽  
pp. 82
Author(s):  
I. V. Korsun

The aim of the paper is to prove the importance of the works performed by Ukrainian scientists for the development of electrodynamics. Some examples of achievements made by Ukrainian scientists in this scientific area include physical theories in such directions as the electrical conductivity, domain structure of ferromagnets, photoelectromotive force in semiconductors, microscopic theory of superconductivity, Shubnikov–de Haas effect, magneto-acoustic resonance, invention of an electric tram, live broadcast of the moving-image signal, distant control of objects by means of radio signals, and arc welding of metals. Most Ukrainian scientists have founded their own scientific schools, which works are recognized throughout the world. They were not only engaged in the scientific and lecturing activities, but also in the popularization of science, reformation of the education system, and social activity.


Author(s):  
Ekkehard Krüger

As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation generated by the strongly correlated atomic-like motion of the electrons in narrow, roughly half-filled "superconducting bands". These are energy bands represented by optimally localized spin-dependent Wannier functions adapted to the symmetry of the material under consideration. The formation of Cooper pairs is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces constraining the electrons to form Cooper pairs. There is theoretical and experimental evidence that only this nonadiabatic mechanism operating in superconducting bands may produce eigenstates in which the electrons form Cooper pairs. These constraining forces stabilize the Cooper pairs in any superconductor, whether conventional or unconventional. Here we report evidence that also the experimentally found superconducting state in bismuth at ambient as well as at high pressure is connected with a narrow, roughly half-filled superconducting band in the respective band structure. This observation corroborates once more the significance of constraining forces in the theory of superconductivity.


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