Anomalous Josephson Current in Junctions with Spin-Polarizing Quantum Point Contacts

TL;DR

This paper demonstrates that a ballistic Josephson junction with a spin-filtering quantum point contact and an in-plane magnetic field exhibits an anomalous supercurrent at zero phase difference and shows supercurrent rectification effects.

Contribution

It reveals the emergence of anomalous supercurrent and rectification effects in Josephson junctions with spin-polarizing quantum point contacts under magnetic fields.

Findings

Anomalous supercurrent appears at zero phase difference.

Large critical current asymmetries are induced by the magnetic field.

Supercurrent rectification effects are observed.

Abstract

We consider a ballistic Josephson junction with a quantum point contact in a two-dimensional electron gas with Rashba spin-orbit coupling. The point contact acts as a spin filter when embedded in a circuit with normal electrodes. We show that with an in-plane external magnetic field an anomalous supercurrent appears even for zero phase difference between the superconducting electrodes. In addition, the external field induces large critical current asymmetries between the two flow directions, leading to supercurrent rectifying effects.