A family of high-temperature ferromagnetic monolayers with locked spin-dichroism-mobility anisotropy: MnNX and CrCX (X=Cl, Br, I; C=S, Se, Te)

TL;DR

This paper predicts a new family of high-temperature ferromagnetic monolayers with large anisotropy and spin-locked dichroism, promising for advanced spintronic and optoelectronic applications.

Contribution

It introduces a family of MnNX and CrCX monolayers with high Curie temperatures, large anisotropy, and unique spin-locked dichroism, expanding the landscape of 2D magnetic materials.

Findings

Curie temperatures predicted from 100 K to nearly 500 K.

Semiconducting bandgaps range from 0.23 to 1.85 eV.

Exhibits large anisotropy in effective masses and mobilities.

Abstract

Two-dimensional magnets have received increasing attention since Cr2Ge2Te6 and CrI3 were experimentally exfoliated and measured in 2017. Although layered ferromagnetic metals were demonstrated at room temperature, a layered ferromagnetic semiconductor with high Curie temperature (Tc) is yet to be unveiled. Here, we theoretically predicted a family of high Tc ferromagnetic monolayers, namely MnNX and CrCX (X=Cl, Br and I; C=S, Se and Te). Their Tc values were predicted from over 100 K to near 500 K with Monte Carlo simulations using an anisotropic Heisenberg model. Eight members among them show semiconducting bandgaps varying from roughly 0.23 to 1.85 eV. These semiconducting monolayers also show extremely large anisotropy, i.e. ~101 for effective masses and ~102 for carrier mobilities, along the two in-plane lattice directions of these layers. Additional orbital anisotropy leads to a spin-locked linear dichroism, in different from previously known circular and linear dichroisms in layered materials. Together with the mobility anisotropy, it offers a spin-, dichroism- and mobility-anisotropy locking. These results manifest the potential of this 2D family for both fundamental research and high performance spin-dependent electronic and optoelectronic devices.