Resolving the order parameter of high-Tcsuperconductors through quantum pumping spectroscopy

Abstract

The order parameter of High-Tc superconductors through a series of experiments has been quite conclusively demonstrated to not be of the normal s − wave type. It is either a pure d x 2 −y 2 -wave type or a mixture of a d x 2 −y 2 − wave with a small imaginary s − wave or dxy − wave component. In this work a distinction is brought out among the four types, i.e., s − wave, d x 2 −y 2 − wave, d x 2 −y 2 + is − wave and d x 2 −y 2 + idxy − wave types with the help of quantum pumping spectroscopy. This involves a normal metal double barrier structure in contact with a High-Tc superconductor. The pumped current, heat and noise show different characteristics with change in order parameter revealing quite easily the differences among these.

Characterizing a high spin magnetic impurity via Andreev reflection spectroscopy

“…Andreev reflection, the process of an incident electron (hole) being retro-reflected as a hole (electron) at an interface with a superconductor has been used as a spectroscopic probe for the amount of polarization in ferromagnet's 1,2 , to determine the pairing symmetry of High T c 3,4 and Ferromagnetic superconductors 4 among many other uses. High spin magnetic impurities (HSM) have been realized around for 20 years or more.…”