Room-temperature half-metallicity in monolayer honeycomb structures of group-V binary compounds with carrier doping

Two-dimensional (2D) half-metallic materials are essential to develop next-generation spintronic devices. Moreover, electrical controllability and room-temperature magnetism are two important ingredients for applications in spintronics. Here, we report findings of a combination of these properties in 2D honeycomb structures of group-V NX (X= N, P, As, Sb, Bi) binary compounds from first-principles calculations. These novel 2D materials are stable semiconductors with indirect band gaps. Hole doping can induce magnetism due to their Mexican-hat band edges and make them half-metals. Some of these half-metals exhibit inverse spin-polarization direction when changing the doping level, which can be achieved by changing the external voltage gate. Monte Carlo simulations based on the Ising model suggest the Curie temperatures of these half-metals are much higher than room temperature. These outstanding properties make monolayer NX promising candidates for spintronic applications.