Thermoelectric effects in normal metal/superconductor interface structures

The thermopower of Andreev interferometers, which are doubly connected loop s in which one arm is a superconductor and one arm is a normal metal, oscil lates as a function of magnetic field with a fundamental period correspondi ng to a flux quantum h/2e through the area of the loop. While the magnetore sistance of an Andreev interferometer is symmetric with respect to the magn etic field, the thermopower can be either symmetric or antisymmetric, depen ding on the topology of the sample. The temperature dependence of the therm opower oscillations is nonmonotonic. This nonmonotonic behavior does not ap pear to be related to the reentrance observed by many groups in the conduct ance of normal-metal/superconductor (NS) structures. (C) 1999 Academic Pres s.