Conductance oscillations with magnetic field of a two-dimensional electron gas-superconductor junction

Abstract

We find the current voltage characteristics of a 2DEG-S interface in magnetic field taking into account the surface roughness. Typically in experiments $L/2R_c\gtrsim 3$, where $L$ is the surface length and $R_c$ is the cyclotron radius. The conductance behaves in experiments usually as $G=g_0+g_1\cos(2\pi\nu+\delta_1)$; higher harmonics, $g_2\cos(4\pi\nu+\delta_2),...$, are hardly seen. Theories based on the assumption of the interface perfectness can hardly describe qualitatively the visibility of the condctance oscillations and the amplitudes of the harmonics: they predict $g_1\sim g_2\sim g_3,...$. Our approach with the surface roughness qualitatively agrees with experiments. It is shown how a disorder at a 2DEG-S interface suppresses the conductance oscillations with $\nu$.