Cubic Rashba spin-orbit interaction of two-dimensional hole gas in strained-Ge/SiGe quantum well

TL;DR

This study investigates the cubic Rashba spin-orbit interaction in a two-dimensional hole gas within strained-Ge/SiGe quantum wells, demonstrating electric control and confirming the cubic nature of the SOI through magnetoconductivity measurements.

Contribution

It provides the first experimental confirmation that heavy holes in strained-Ge exhibit purely cubic Rashba spin-orbit interaction, with electric field tunability.

Findings

Weak anti-localization observed in magnetoconductivity.

WAL feature fully described by cubic Rashba SOI theory.

Electric field enables control of the Rashba SOI.

Abstract

The spin-orbit interaction (SOI) of the two-dimensional hole gas in the inversion symmetric semiconductor Ge is studied in a strained-Ge/SiGe quantum well structure. We observed weak anti-localization (WAL) in the magnetoconductivity measurement, revealing that the WAL feature can be fully described by the k-cubic Rashba SOI theory. Furthermore, we demonstrated electric field control of the Rashba SOI. Our findings reveal that the heavy hole (HH) in strained-Ge is a purely cubic-Rashba-system, which is consistent with the spin angular momentum mj = +-3/2 nature of the HH wave function.