Detecting Spin-Polarized Currents in Ballistic Nanostructures

TL;DR

This paper presents a mesoscopic system that measures spin polarization of currents in nanostructures, demonstrating high polarization levels using a transverse focusing geometry under strong magnetic fields.

Contribution

It introduces a novel spin polarizer/analyzer system utilizing transverse focusing to measure spin polarization in ballistic nanostructures, achieving over 80% polarization.

Findings

Spin polarizations >80% at 300mK and 7T in-plane field.

Effective measurement of spin polarization using transverse focusing geometry.

Demonstration of spin-dependent voltage variation in quantum point contacts.

Abstract

We demonstrate a mesoscopic spin polarizer/analyzer system that allows the spin polarization of current from a quantum point contact in an in-plane magnetic field to be measured. A transverse focusing geometry is used to couple current from an emitter point contact into a collector point contact. At large in-plane fields, with the point contacts biased to transmit only a single spin (g < e^2/h), the voltage across the collector depends on the spin polarization of the current incident on it. Spin polarizations of greater than 80% are found for both emitter and collector at 300mK and 7T in-plane field.