Scanning Tunneling Spectroscopy Studies of Current-Carrying Superconductors

Understanding how a superconducting order parameter evolves in the current-carrying state is of fundamental physical importance. In this talk we present novel applications of scanning tunneling spectroscopy (STS) on current-carrying superconductors, with the current either directly applied [D. Zhang et al., Phys. Rev. B 70, 172508 (2004)] or induced by a magnetic field [G. Deutscher, Rev. Mod. Phys. 77, 109 (2005)]. We will discuss STS measurements on YBa2Cu3O7 thin-film strips under directly-applied current, showing suppression of the d- wave Andreev states [J. Ngai et al. Phys. Rev. B 72, 054513 (2005)]. We will also discuss more recent STS experiments on high-Tc and other superconductors, performed under magnetic field-induced currents.