Spin-valley locking for in-gap quantum dots in a MoS2 transistor

Abstract

Spins confined to atomically-thin semiconductors are being actively explored as quantum information carriers. In transition metal dichalcogenides (TMDCs), the hexagonal crystal lattice gives rise to an additional valley degree of freedom with spin-valley locking and potentially enhanced spin life- and coherence times. However, realizing well-separated single-particle levels, and achieving transparent electrical contact to address them has remained challenging. Here, we report well-defined spin states in a few-layer MoS${}_2$ transistor, characterized with a spectral resolution of $\sim 50\mu$eV at $T_{\text{el}}=150$~mK. Ground state magnetospectroscopy confirms a finite Berry-curvature induced coupling of spin and valley, reflected in a pronounced Zeeman anisotropy, with a large out-of-plane $g$-factor of $g_{\perp }\simeq 8$. A finite in-plane $g$-factor ($g_{\parallel }\simeq 0.55-0.8$) allows us to quantify spin-valley locking and estimate the spin-orbit splitting $2{\Delta }_{\mathrm{SO}}\sim 100\mu$eV. The demonstration of spin-valley locking is an important milestone towards realizing spin-valley quantum bits.

7 pages, 3 figures