Effects of Magnetic Field on Josephson Current in SNS System

TL;DR

This study investigates how magnetic fields influence Josephson currents in SNS systems with a 2D electron gas, revealing dependence on the width of the normal metal and showing different interference patterns.

Contribution

It demonstrates the impact of normal metal width on magnetic field dependence of Josephson currents, highlighting transitions from Fraunhofer-like patterns to Aharonov-Bohm interference effects.

Findings

Wide normal metal shows Fraunhofer-like and Aharonov-Bohm oscillations.

Narrower normal metal deviates from Fraunhofer pattern.

Oscillation amplitude decreases as the normal metal narrows.

Abstract

The effect of a magnetic field on Josephson current has been studied for a superconductor/normal-metal/superconductor (SNS) system, where N is a two-dimensional electron gas in a confining potential. It is found that the dependence of Josephson currents on the magnetic field are sensitive to the width of the normal metal. If the normal metal is wide and contains many channels (subbands), the current on a weak magnetic field shows a dependence similar to a Fraunhofer-pattern in SIS system and, as the field gets strong, it shows another type of oscillatory dependence on the field resulting from the Aharonov-Bohm interference between the edge states. As the number of channels decreases (i.e. normal metal gets narrower), however, the dependence in the region of the weak field deviates from a clear Fraunhofer pattern and the amplitude of the oscillatory dependence in the region of the strong field is reduced.