Quantum Imaging of Single-Atom Spin-Splitting in a Monolayer Semiconductor

TL;DR

This study demonstrates that individual Mn dopants in monolayer MoS2 exhibit strong spin splitting and act as magnetic moments, with implications for spintronics and magnetic properties in two-dimensional materials.

Contribution

The paper provides experimental evidence of spin splitting in Mn dopants in MoS2 and extends magnetic measurements from atomic to macroscopic scales using STM/STS and MOKE techniques.

Findings

Mn dopants show strong spin splitting.

Single Mn atoms act as active magnetic moments.

Magnetization increases with Mn concentration.

Abstract

Theoretical work has suggested that monolayer MoS2 doped with Mn should behave as a two-dimensional dilute magnetic semiconductor, which would open up possibilities for spintronic applications, device physics, and novel ground states. The magnetic properties on Mn dopants in MoS2 are dependent on the mid-gap impurity states of said dopants as well as the sites of dopant incorporation and dopant concentration. In this work we use STM/STS to characterize multiple impurity types associated with Mn dopants in MoS2, and use ring features that appear in spectral maps due to tip-induced band bending to investigate the nature of the mid-gap impurity states. The doublet nature of the rings and comparison to DFT calculations show that the Mn states exhibit strong spin splitting which can be quantified. We used scanned MOKE experiments to extend these magnetization measurements from atomic scale to mm scales, and detect the spin susceptibility signal which increases with Mn concentration. These experiments show that single Mn atoms in MoS2 function as active unscreened magnetic moments in the TMD monolayer, and can be harnessed for spin physics applications and science.