Magnetism between magnetic adatoms on monolayer NbSe₂

Abstract

In this work, we report on an ab-initio computational study of the electronic and magnetic properties of transition metal adatoms on a monolayer of NbSe2. We demonstrate that Cr, Mn, Fe and Co prefer all to sit above the Nb atom, where the d states experience a substantial hybridization. The inter-atomic exchange coupling is shown to have an oscillatory nature accompanied by an exponential decay, in accordance with what theory predicts for a damped Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Our results indicate that the qualitative features of the magnetic coupling for the four investigated adatoms can be connected to the fine details of their Fermi surface. In particular, the oscillations of the exchange in Fe and Co are found to be related to a single nesting vector, connecting large electrons and hole pockets. Most interestingly, this behavior is found to be unaffected by changes induced on the height of the impurity, which makes the magnetism robust to external perturbations. Considering that NbSe2 is a superconductor down to a single layer, our research might open the path for further research into the interplay between magnetic and superconducting characteristics, which could lead to novel superconductivity engineering.

Magnetic doping in transition metal dichalcogenides

“…When switching from a monolayer to a bilayer sample, a hysteresis loop was observed with minima at ±15 mT under backward and forward scans (figure 6(g)), yielding ferromagnetic behavior. Although RKKY interactions [29,30] are usually responsible for magnetic exchange coupling in metallic multilayers, superexchange mechanisms tend to govern magnetism as PtSe 2 approaches the monolayer limit, due to its semiconducting properties. Overall, monolayer PtSe 2 exhibited long-range antiferromagnetic ordering while bilayers exhibited ferromagnetism, and it is clear that the possible applications of these samples in electronic devices with graphene electrodes can be effectively used to detect such magnetism.…”

“…The adatoms case will not be discussed in this review, as it does not represent a useful application of controlled and homogenous defect formation. It can, however, still lead to magnetism [29][30][31] in 2D materials.…”