Half-metallicity and spin-valley coupling in 5d transition metal substituted monolayer MnPSe3

Abstract

Monolayer MnPSe₃, a typical two-dimensional semiconducting material with intrinsic antiferromagnetic characteristics, has drawn intense research interest due to its potential applications in multifunctional electronic devices. Herein, we report first-principles calculations on the electronic structures, magnetic properties and potential applications of 5d transition metal (TM) substituted MnPSe₃. Introducing different 5d TM impurities can bring out different magnetic configurations for substituted systems. Strong orbital hybridization reveals that covalent bonds form between TMs and defective MnPSe₃. Hf-, Ta-, W-, Re-, Os-, Pt-, Au- and Hg-substituted MnPSe₃ demonstrate spin-polarized semiconducting properties, and they can be further subdivided as half semiconductors and bipolar magnetic semiconductors based on the spin direction of the conduction band minimum and valence band maximum. Furthermore, by considering spin–orbit coupling, spin and valley degeneracy splitting are achieved simultaneously in Hg-substituted MnPSe₃. A data storage device prototype is proposed for future applications based on the anomalous valley Hall effects in this ferrovalley material. In contrast, for Ir-substituted MnPSe₃, one spin channel retains semiconducting characteristics while the other crosses the Fermi level, yielding half-metallic behavior with a high spin polarization of 100%. Through selective 5d TM doping, MnPSe₃ can transform into a spin-polarized semiconductor or even into a half-metal, which facilitates the promising applications of monolayer MnPSe₃ for highly efficient spintronic and valleytronic devices.