- Broida 1640
Sri Raghu, Stanford University
Superconductivity in elemental metals such as Hg and Al forms out of a gas of long-lived electron-like excitations. It has been well understood for nearly 6 decades within the framework of Bardeen, Cooper and Schrieffer (BCS) theory. By contrast, many "strongly correlated" materials, such as the cuprates, heavy fermion systems, and iron pnictide materials, host superconductivity that condenses out of strongly interacting metals without long-lived electronic excitations. The manner in which such a short-lived, "dying" sea of electrons gives way to enhanced superconductivity has remained one of the most challenging and exciting questions of modern condensed matter theory.
In this talk, I will review some of the fascinating experimental developments that point towards the simultaneous enhancement of superconductivity and the destruction of long-lived electron excitations. Both these effects tend to occur near continuous T=0 phase transitions known as quantum critical points. I will discuss ongoing efforts to describe the manner in which superconductivity arises in metals close to quantum critical points and will highlight fundamental challenges that remain in our understanding of such phenomena.