John Bardeen and the BCS Theory of Superconductivity
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is student J. Robert Schrieffer, and postdoctoral candidate Léon Cooper solved it in 1957.
T h i s article draws in part on a manuscript by L. Hoddeson and V. Daitch, Centle Genius: The Life and Physics of John Bardeen; and on sections on superconductivity by L. Hoddeson and G. Baym, "Collective Phenomena," in Ont oflhc Crystal Maze: A History ofSolid State Physics, 1900-1960, edited by L. Hoddeson, E. Braun, J. Teichmann, and S. Weart (Oxford University Press, New York, 1992) p. 489.
Arriving at Princeton in the fall of 1933, Bardeen boldly turned his back on the secure engineering post he had held for the last three years at Gulf Research Laboratory in Pittsburgh. At the height of the Great Dépression he enrolled in Princeton's graduate program in mathematics. Abandoning his initial idea of working with Einstein, who also arrived
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Princeton and Harvard Bardeen probably first encountered the problem of explaining superconductivity between 1933 and 1935, when he was a graduate student at Princeton. He was entering the new field of the quantum theory of solids and avidly reading its pioneering papers. In their comprehensive review published in the 1933 Handbuch der Physik, H a n s Bethe and Arnold Sommerfeld identified superconductivity as the only solid-state problem that still resisted treatment by the quantum theory. 2 While we hâve no évidence Bardeen even attempted to attack the problem in that period, he likely entertained the thought, for he was amply endowed with compétitive spirit.
The process of working on many-body problems that could not yet be solved using the existing theoretical framework helped Bardeen prépare for the major challenge of his career.
at Princeton that fall, Bardeen became the second graduate student of the young, but already quite eminent, mathematical physicist, Eugène Wigner. Wigner was just then excited about em ploying quantum mechanics to explain the multitude of behaviors and properties of real materials. He was working with his first graduate student, Frederick Seitz, on developing a simple approximation method for calculating the energy bands of sodium, the first nonideal material to which the q u a n t u m theory of metals was applied. Wigner was bothered by the fact that his work with Seitz failed to account for the interactions between électrons. He recognized that his own attempts to add an électron interaction term in a study of the cohesive energy of metals was only the beginning of the development of a "many-body" theory, in which the interactions between électrons, as well as between the électrons and lattice are properly dealt with. 3 Wigner posed the fundamental question to Bardeen: How do the électrons inside metals interact? The problem so enticed the student that he never let go of it throughout his physics career of almost 60 years. He returned to it, for example, in his doctoral thesis, in which he calculated a metal's "work function" (the energy needed to remove an électron from the métal), 4 in his study of semiconductor surface states in 1946—a major ste
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