Biaxial ([110]) strain influence on the n-type half-metallicity and Curie temperature of Tc-doped Janus MoSSe monolayer

Abstract

2D materials having stable half-metallic (HM) ferromagnetism are pivotal for multifunctional spintronic devices such as non-volatile random access magnetic memories and magnetic sensors. Using ab-initio calculations, we theoretically demonstrate that the electron-doped (Tc-doping at Mo site) Janus MoSSe monolayer (ML) is an n-type HM ferromagnetic (FM) with a charge carrier density of 2.9 × 1012 cm−2, which is thermally, mechanically, and dynamically stable. In addition, the large HM energy band gap of 1.63 eV is high enough to establish the long spin mean free path, high spin-filtering performance, and to avoid thermally excited spin-flip transition. Simultaneously, the calculated Curie temperature (TC) using a classical 2D Heisenberg model is 175 K, which indicates that Tc-doped MoSSe ML could be a stable FM structure. Interestingly, it is revealed that TC approaches to room temperature value for Fe 3d transition metals doping at Mo site, which makes the Fe-doped MoSSe ML highly desired for device application. Moreover, a direct-to-indirect band gap transition occurs in the pristine MoSSe ML for a biaxial ([110]) compressive/tensile (comp./tens.) strain of ≥−/+2%. It is also predicted that the n-type HM nature of the Tc-doped ML is very sensitive against applied strains and can be preserved under the -3% comp. to +2% tens. strain range. Along with this, the system undergoes a transition from FM to a non-magnetic state at a critical tensile strain of ＋ 5%, while the FM state remains robust under applied comp. strains. Correspondingly, it is also proposes that TC can be enhanced when a moderate compr. strain is adjusted. Hence, the present work are supposed to trigger further experimental studies to probe HM FM behavior in various Janus MLs by the combined effect of electron doping and strain engineering.