Consequences of unconventional order parameter symmetry-high critical temperature structures

Abstract

We review some aspects of the physics of high temperature superconductivity (HTS) related to coherent phenomena and unconventional pairing symmetry. We discuss the role of the Josephson effect as a very powerful probe of the underlying physics of HTS, concentrating on phase-sensitive experiments. We then proceed to some consequences of d-wave symmetry, including possible broken time-reversal symmetry, Andreev bound states, and the presence of an imaginary component of the order parameter (OP) in the presence of surfaces and interfaces. Finally we discuss some aspects of HTS grain boundary Josephson junctions which allow fundamental studies and potential applications, in particular the possibility, of employing grain boundary Josephson junctions for π-circuitry and d-wave qubit arrays.