An Unusual Dresselhaus Spin-Orbit Contribution of Even Order in Momentum

TL;DR

This paper uncovers an unconventional quadratic Dresselhaus spin-orbit term in semiconductors, revealing new quantum phenomena and suggesting novel spintronic applications by exploiting even-order momentum effects.

Contribution

It demonstrates the emergence of an even-order quadratic Dresselhaus SO term via interband effects in semiconductor heterostructures, challenging the conventional odd-order understanding.

Findings

Discovery of quadratic Dresselhaus SO term from interband effects

Observation of hybridized swirling spin textures and anisotropic dispersion

Identification of novel quantum phenomena like Zitterbewegung and opposite spin evolution

Abstract

The spin-orbit (SO) coupling is conventionally known to manifest as \emph{odd} functions of momentum. Here, through both model calculations and symmetry analysis along with the method of invariants, we reveal that, in ordinary semiconductor heterostructures, a \emph{quadratic} Dresselhaus SO term -- inheriting from its bulk crystal form -- emerges via the interband effect, while complying with time-reversal and spatial symmetries. Furthermore, we observe that this unusual SO term gives rise to a range of striking quantum phenomena, including hybridized swirling texture, anisotropic energy dispersion, avoided band crossing, longitudinal \emph{Zitterbewegung}, and opposite spin evolution between different bands in quantum dynamics. These stand in stark contrast to those associated with the usual \emph{linear} SO terms. Our findings uncover a previously overlooked route for exploiting interband effects and open new avenues for spintronic functionalities that leverage unusual SO terms of \emph{even} orders in momentum.