  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.
