Spin relaxation of localized electrons in monolayer MoSe$_2$: importance of random effective magnetic fields

TL;DR

This study investigates spin relaxation mechanisms of localized electrons in monolayer MoSe$_2$ on EuS, highlighting the role of random magnetic fields and hyperfine interactions in spin dynamics at low temperatures.

Contribution

It provides new insights into the spin relaxation processes of localized electrons in MoSe$_2$, emphasizing the impact of random effective magnetic fields and anisotropic g-factors.

Findings

Localized electrons dominate spin signals below 15 K.

Random magnetic fields significantly influence spin relaxation.

Measured in-plane g-factor is approximately 0.1.

Abstract

We study the Hanle and spin polarization recovery effects on resident electrons in a monolayer MoSe$_2$ on EuS. We demonstrate that localized electrons provide the main contribution to the spin dynamics signal at low temperatures below 15~K for small magnetic fields of only a few mT. The spin relaxation of these electrons is determined by random effective magnetic fields due to a contact spin interaction, namely the hyperfine interaction with the nuclei in MoSe$_2$ or the exchange interaction with the magnetic ions of the EuS film. From the magnetic field angular dependence of the spin polarization we evaluate the anisotropy of the intervalley electron $g$-factor and the spin relaxation time. The non-zero in-plane $g$-factor $|g_x|\approx 0.1$, the value of which is comparable to its dispersion, is attributed to randomly localized electrons in the MoSe$_2$ layer.