Strong coupling between a permalloy ferromagnetic contact and a helical edge channel in a narrow HgTe quantum well

TL;DR

This study demonstrates strong, spin-sensitive coupling between a permalloy ferromagnetic contact and helical edge channels in a narrow HgTe quantum well, enabling selective probing of topological edge states.

Contribution

It provides experimental evidence of strong ferromagnetic coupling to helical edge channels in HgTe quantum wells, highlighting potential for spin-sensitive edge state manipulation.

Findings

Strong asymmetry in edge potential distribution observed.

Evidence of proximity magnetization effects.

Selective, spin-sensitive contact to helical edge states achieved.

Abstract

We experimentally investigate spin-polarized electron transport between a permalloy ferromagnet and the edge of a two-dimensional electron system with band inversion, realized in a narrow, 8~nm wide HgTe quantum well. In zero magnetic field, we observe strong asymmetry of the edge potential distribution with respect to the ferromagnetic ground lead. This result indicates, that the helical edge channel, specific for the structures with band inversion even at the conductive bulk, is strongly coupled to the ferromagnetic side contact, possibly due to the effects of proximity magnetization. It allows selective and spin-sensitive contacting of helical edge states.