Spin Bias Measurement Based on a Quantum Point Contact

TL;DR

This paper proposes a method to detect spin bias using a quantum point contact, demonstrating large charge bias signals and the ability to determine spin polarization direction with magnetic fields.

Contribution

It introduces a practical approach to measure spin bias via charge bias in a QPC, utilizing simple devices like a QPC or STM tip, enhanced by magnetic fields.

Findings

Large charge bias induced by spin bias in QPCs.

Charge bias can be used to detect spin bias effectively.

Magnetic fields help determine the spin polarization direction.

Abstract

Electron charge transport through a quantum point contact (QPC) driven by an asymmetric spin bias is studied. A large charge current is induced when the transmission coefficient of the QPC jumps from one integer plateau to the next. Furthermore, for an open external circuit, the induced charge bias instead of the charge current is found to be quite large. It provides an efficient and practical way to detect spin bias by using a very simple device, a QPC or a STM tip. In addition, with the aid of magnetic field, polarization direction of the spin bias can also be determined.