Electric dipole spin resonance in systems with a valley dependent g-factor

TL;DR

This paper provides a theoretical analysis of electric dipole spin resonance in Si/SiGe quantum dots, highlighting how valley-dependent g-factors and valley relaxation contribute to spin dephasing, aligning with recent experimental observations.

Contribution

It introduces a microscopic theory of valley dependent g-factors and explores their role in spin dephasing mechanisms in Si/SiGe quantum dots.

Findings

Valley relaxation causes electron spin dephasing.

Valley-dependent g-factors influence spin control.

Results agree with recent experimental data.

Abstract

In this theoretical study we qualitatively and quantitatively investigate the electric dipole spin resonance (EDSR) in a single Si/SiGe quantum dot in the presence of a magnetic field gradient, e.g., produced by a ferromagnet. We model a situation in which the control of electron spin states is achieved by applying an oscillatory electric field, inducing real-space oscillations of the electron inside the quantum dot. One of the goals of our study is to present a microscopic theory of valley dependent $g$-factors in Si/SiGe quantum dots and investigate how valley relaxation combined with a valley dependent $g$-factor leads to a novel electron spin dephasing mechanism. Furthermore, we discuss the interplay of spin and valley relaxations in Si/SiGe quantum dots. Our findings suggest that the electron spin dephases due to valley relaxation, and are in agreement with recent experimental studies [Nature Nanotechnology 9, 666-670 (2014)].