Unidirectional Transmission of Electrons in a Magnetic Field Gradient

TL;DR

This paper experimentally demonstrates unidirectional electron transmission in a hybrid ferromagnet-semiconductor device with magnetic barriers, revealing time-reversal asymmetry due to asymmetric electron trajectories in magnetic field gradients.

Contribution

The study provides the first experimental evidence of time-reversal asymmetry in electron transport caused by magnetic field gradients in a hybrid device.

Findings

Reversal of magnetic barriers changes the bend resistance sign.

Asymmetric transmission of electron trajectories observed.

Landauer-Buttiker theory explains the asymmetry.

Abstract

The work presents an experimental demonstration of time-reversal asymmetry of electron states propagating along boundary separating areas with opposite magnetic fields. For this purpose we have fabricated a hybrid ferromagnet-semiconductor device in form of a Hall cross with two ferromagnets deposited on top. The magnets generated two narrow magnetic barriers of opposite polarity in the active Hall area. We have observed that if the signs of the barriers are reversed, the bend resistance changes its sign. Using the Landauer-Buttiker theory, we have demonstrated that this is a direct consequence of asymmetric transmission of the "snake" and the "cycloidal" trajectories formed the boundary separating the regions with opposite magnetic field directions.