Design and Modulation of Novel 2D Ferromagnetic Materials

Jijun Zhao*

School of Physics, Dalian University of Technology, Dalian, 116024, China

ABSTRACT: Two-dimensional (2D) ferromagnets have attracted wide attentions because of their importance in spintronics. In experiments, a variety of metallic and semiconducting 2D ferromagnets have been synthesized, but usually having low Curie temperature (T_C). Thus, it is desirable to search and design more ferromagnets with high Curie temperature. Starting from 2D transition metal compounds with less than six atom per unit cell, we performed screening and isoelectronic substitution to derive unprecedented 2D ferromagnetic semiconductors, i.e. CrSCl and CrSeBr with T_C = 500 K. We searched for novel 2D ferromagnets in transition metal borides and phosphides and designed monolayers of MnB (T_C = 350 K) and Co₂P (T_C = 580 K). Furthermore, we proposed to find novel p-state 2D ferromagnets from non-stoichiometric materials and designed YN₂ monolayer with T_C above 330 K and K₂N monolayer with three phases and T_C up to 1180 K. YN₂ monolayer is also a Dirac half-metal with ultrahigh Fermi velocity. Finally, we utilized proximity effect of bulk semiconductor substrate or self-intercalation to convert bilayer CrI₃ into robust ferromagnet with relatively high temperature.

Keywords: 2D ferromagnet; materials design; Curie temperature; ferromagnetic coupling.