# Optically and electrically controllable adatom spin-orbital dynamics in transition metal dichalcogenides

## TL;DR

This paper investigates how magnetic adatoms on transition-metal dichalcogenides can have their spin and orbital states controlled optically and electrically, revealing tunable quantum and classical spin regimes with potential for spintronic applications.

## Contribution

It demonstrates the orbital-dependent exchange interactions and magnetic anisotropy of adatoms on MX$_2$, and shows how their spin states can be manipulated electrically and optically.

## Key findings

- Adatoms exhibit orbitally dependent spin-flip scattering rates.
- Single Co, Rh, Ir adatoms on MoS$_2$ can have sizable magnetic anisotropy.
- Behavior can be tuned from Kondo regime to classical spintronics regime.

## Abstract

We analyze the interplay of spin-valley coupling, orbital physics and magnetic anisotropy taking place at single magnetic atoms adsorbed on semiconducting transition-metal dichalcogenides, MX$_2$ (M = Mo, W; X = S, Se). Orbital selection rules turn out to govern the kinetic exchange coupling between the adatom and charge carriers in the MX$_2$ and lead to highly orbitally dependent spin-flip scattering rates, as we illustrate for the example of transition metal adatoms with $d^9$ configuration. Our ab initio calculations suggest that $d^9$ configurations are realizable by single Co, Rh, or Ir adatoms on MoS$_2$, which additionally exhibit a sizable magnetic anisotropy. We find that the interaction of the adatom with carriers in the MX$_2$ allows to tune its behavior from a quantum regime with full Kondo screening to a regime of "Ising spintronics" where its spin-orbital moment acts as classical bit, which can be erased and written electronically and optically.