Conducting Electrons:
Orchestrating a Theory of Low-Temperature Superconductivity

Ben Luey

Date: April $3^{rd}$, 2002

Abstract:

Discovered in 1911, superconductivity remained an amazing, but unexplained, phenomenon for almost half a century. Despite years of diligence by many physicists - including Einstein, Heisenberg, Pauli, and Bohr - a microscopic theory of superconductivity, a theory that explained the behavior inside a superconducting metal, did not exist until 1957 when J. Bardeen, L. Cooper, and J. R. Schrieffer created a theory (BCS theory) that explained what had been troubling physicists for almost 50 years.

This paper will cover the development of theories of low-temperature, type-I superconductivity. The first section will discuss the achievements in the liquefaction of gases that lead to the discovery of superconductivity, followed by an overview of the experimental properties of superconductors and a look at some of the early theories attempting to explain these properties. The next section will give a historical account of the formation of BCS theory, and then an explanation of the basics of BCS theory, including Cooper pairing, the energy gap, and the superconducting ground state wavefunction. After briefly showing some experimental evidence for BCS theory, the paper will conclude with a brief discussion of type-II and high-temperature superconductors and their applications.