Strong and Tunable Spin-Orbit Coupling of One-Dimensional Holes in Ge/Si Core/Shell Nanowires

TL;DR

This study demonstrates that Ge/Si core/shell nanowires exhibit strong, tunable spin-orbit coupling, with potential applications in spintronics, by analyzing their low-temperature magneto-transport properties and showing electric field modulation of spin-orbit strength.

Contribution

We show that the spin-orbit coupling in Ge/Si nanowires can be significantly tuned by an external electric field, revealing their potential for spintronic devices.

Findings

Negative magneto-conductance indicates weak antilocalization.

Spin-orbit coupling strength can be modulated by over five times with electric field.

Temperature and gate dependence of phase coherence and spin relaxation were characterized.

Abstract

We investigate the low-temperature magneto-transport properties of individual Ge/Si core/shell nanowires. Negative magneto-conductance was observed, which is a signature of one-dimensional weak antilocalization of holes in the presence of strong spin-orbit coupling. The temperature and back gate dependences of phase coherence length, spin-orbit relaxation time, and background conductance were studied. Specifically, we show the spin-orbit coupling strength can be modulated by more than five folds with an external electric field. These results suggest the Ge/Si nanowire system possesses strong and tunable spin-orbit interactions and may serve as a candidate for spintronics applications.