Cong Wang, Xieyu Zhou, Linwei Zhou, Ninghua Tong, Zhong-Yi Lu, Wei Ji*
Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, P.R. China
DOI:10.1016/j.scib.2019.02.011 Publication Date: March 15, 2019
Two dimensional magnets have received increasing attentions 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. At least eight members among them show semiconducting bandgaps varying from roughly 0.24 eV to 2.42 eV. These semiconductor monolayers also show extremely large anisotropy, i.e. ~102 for effective masses and ~103 for carrier mobilities, along the two lattice directions of these layers. Additional orbital anisotropy leads to a strong spin-selective chiral elliptic 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.