Andreev interferometry as a probe of superconducting phase correlations in the pseudogap regime of the cuprates

Andreev interferometry—the sensitivity of the tunneling current to spatial variations in the local superconducting order at an interface—is proposed as a probe of the spatial structure of the phase correlations in the pseudogap state of the cuprate superconductors. To demonstrate this idea theoretically, a simple tunneling model is considered, via which the tunneling current is related to the equilibrium phase-phase correlator in the pseudogap state. These considerations suggest that measurement of the low-voltage conductance through mesoscopic contacts of varying areas provides a scheme for accessing phase-phase correlation information. For illustrative purposes, quantitative predictions are made for a model of the pseudogap state in which the phase (but not the amplitude) of the superconducting order varies randomly, and does so with correlations consistent with certain proposed pictures of the pseudogap state. © 2000 The American Physical Society