Spin-orbit enhancement in Si/SiGe heterostructures with oscillating Ge concentration
| Autor: | Benjamin D. Woods, M. A. Eriksson, Robert Joynt, Mark Friesen |
|---|---|
| Rok vydání: | 2022 |
| Předmět: | |
| DOI: | 10.48550/arxiv.2210.01700 |
| Popis: | We show that Ge concentration oscillations within the quantum well region of a Si/SiGe heterostructure can significantly enhance the spin-orbit coupling of the low-energy conduction-band valleys. Specifically, we find that for Ge oscillation wavelengths near $\lambda = 1.57~\text{nm}$ with an average Ge concentration of $\bar{n}_{\text{Ge}} = 5\%$ in the quantum well region, a Dresselhaus spin-orbit coupling is induced, at all physically relevant electric field strengths, which is over an order of magnitude larger than what is found in conventional Si/SiGe heterostructures without Ge concentration oscillations. This enhancement is caused by the Ge concentration oscillations producing wave-function satellite peaks a distance $2 \pi/\lambda$ away in momentum space from each valley, which then couple to the opposite valley through Dresselhaus spin-orbit coupling. Our results indicate that the enhanced spin-orbit coupling can enable fast spin manipulation within Si quantum dots using electric dipole spin resonance in the absence of micromagnets. Indeed, our calculations yield a Rabi frequency $\Omega_{\text{Rabi}}/B > 500~\text{MHz/T}$ near the optimal Ge oscillation wavelength $\lambda = 1.57~\text{nm}$. Comment: 19 pages, 11 figures |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|