GIANT CONDUCTANCE OSCILLATIONS IN SUPERCONDUCTING PHASE GRADIOMETERS

A new class of superconductivity-enhanced, quasi-particle interference effects (SEQUINs) is suggested, based on interference from the order parameter phase gradient of a single superconductor (S) in contact with a normal metallic lead (N) of finite width M. By solving the Bogoliubov-de Gennes equation in two dimensions, it is predicted that the electrical conductance will oscillate as the phase gradient v at 90 degrees to the interface is increased, with period ($) over bar v = 2 pi/M. This effect is enhanced by the presence of a Schottky barrier at the interface and is also present in N-S-N structures. The size of the effect scales with the number of open channels and can be much greater than e(2)/h.