Ab Initio Identification And Characterization Of 2D Transition Metal Disulfide Half-Metallic Ferromagnets

Abstract

Graphene's successful synthesis and unique properties have attracted an immense amount of interest from physicists, chemists and materials scientists. Recently, studies on single-layer MoS2 and other two-dimensional (2D) materials have shown that 2D materials can exhibit fascinating and technologically useful properties, which differ from their bulk counterparts. Here, we use density functional theory (DFT) to identify and characterize transitional metal disulfides with the goal to discover low-energy 2D materials with magnetic properties. To ensure the stability of our proposed 2D materials, we investigate their energetic stability by calculating their formation energy relative to their bulk counterparts. We also determine their dynamical stability by computing their phonon spectra. To overcome the failure of semi-local exchange-correlation functionals in DFT when investigating systems whose ground state is characterized by a more pronounced localization of electrons, we employ the DFT + U method for energy and phonon calculations and the HSE06 hybrid functional for electronic band structure calculations. We identify five low-energy and dynamically stable 2D materials, three of which are magnetically polarized. Through the investigation of the electronic band structures of these stable materials, we identify two half-metallic ferromagnets, which behave as a semiconductor or insulator for electrons of one spin orientation, and behave as a metal for electrons of the opposite spin orientation. These materials, we believe, would have wide application in spintronics if successfully synthesized.