Abstract
In this work, the structural and magnetic properties of Cr doping at possible sites in the InS monolayer were systematically investigated by density functional theory. The pristine InS monolayer is a diamagnetic semiconductor material of an indirect band gap. Based on our results, doping of the Cr atom at possible lattice sites in the InS monolayer tuned the band gap and induced ferromagnetism in a diamagnetic InS monolayer. Furthermore, the dopant atom induces impurity states within the band gap of the pristine InS monolayer. Thermodynamically, Cr-In is the most stable site among all possible doping sites under growth conditions. Therefore, we chose the In site for further investigations. The InS monolayer doped with Cr at the S site shows a half-metallic nature, which is the basic need for the next generation of spintronic devices. Finally, we studied the ferromagnetic (FM) and anti-ferromagnetic (AFM) interactions of dopant atoms by varying the interaction length between the two dopant sites. To estimate the Curie temperature T-c, the calculated exchange coupling parameter J=1.056 meV for two Cr atoms doped at far positions. We found that two Cr atoms lying at the near separation distance prefer the AFM state, while two Cr atoms lying at the far separation distance prefer the FM state. T-c estimated for the latter arrangement is 8.17 K (45.27 K) at equilibrium (-3% biaxial strain). We conclude that the substitutional doping of Cr atom(s) in the 2D InS monolayer improved their electronic and magnetic properties, indicating that InS:Cr is a potential candidate for spintronic devices.
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