Strain and point defects in MnSe2 ferromagnetic monolayers*

After the isolation of graphene in 2004, a vast amount of 2D materials have been studied. However, most 2D materials known are non-magnetic, which limits their potential technological applications. Although magnetic moments have been induced by defects, doping or interaction with a substrate, there was not a case of intrinsic ferromagnetism in a monolayer. This situation changed recently with the exfoliation of CrI₃ and Cr₂Ge₂Te₆ monolayers. Among these materials, MnSe₂ and MnS₂ have been predicted as stable ferromagnetic monolayers by first-principles calculations [1], and MnSe₂ is currently a subject of experimental efforts to grow thin and monolayer samples [2].
In this work, we present a detailed analysis of the effects that point defects and strain have in the electronic structure of the material using a GGA+U approach on a monolayer of MnSe₂. Our calculations result in the gap changing by 8% under a 1% biaxial strain. We also analyze the consequences of different point defects on the ferromagnetic ordering and self-doping, with the objective of improving the understanding of the material mechanisms at play.
[1] M. Kan, S. Adhikari, and Q. Sun, Phys. Chem. Chem. Phys. 16, 4990 (2014).
[2] R. Kawakami, EP2DS-22 (2017)