Anomalous spin-resolved point-contact transmission of holes due to cubic Rashba spin-orbit coupling

TL;DR

This paper demonstrates how strong cubic Rashba spin-orbit coupling in hole-based quantum point contacts causes anomalous spin-resolved transmission, with controllable spin polarization sign inversion due to subband crossing and anticrossing effects.

Contribution

It provides experimental evidence and theoretical explanation for spin-split subband crossing and polarization inversion in hole gases with strong spin-orbit interaction.

Findings

Finite wave vector crossing of spin-split subbands observed.

Magnetic field and asymmetric potential induce anticrossing.

Spin polarization sign can be inverted by controlling spin-splitting.

Abstract

Evidence is presented for the finite wave vector crossing of the two lowest one-dimensional spin-split subbands in quantum point contacts fabricated from two-dimensional hole gases with strong spin-orbit interaction. This phenomenon offers an elegant explanation for the anomalous sign of the spin polarization filtered by a point contact, as observed in magnetic focusing experiments. Anticrossing is introduced by a magnetic field parallel to the channel or an asymmetric potential transverse to it. Controlling the magnitude of the spin-splitting affords a novel mechanism for inverting the sign of the spin polarization.