Half-metallic YN₂ monolayer: dual spin filtering, dual spin diode and spin Seebeck effects

Most of the pristine graphene-like two-dimensional materials have been found to be non-magnetic, and the emergence of magnetism usually needs an external electric field, substrate, strain, vacancy, or doping, which is not easily controlled in an experiment, limiting the potential applications in spintronics. Very recently, layered transition-metal dinitrides were explored experimentally and theoretically, and a pristine YN₂ monolayer was predicted to be a half-metallic ferromagnet with a graphene-like structure. To demonstrate the possible spintronic applications, herein, we designed spintronic devices based on the half-metallic YN₂ monolayer, and found perfect dual spin filtering and dual spin diode effects when a bias voltage was applied. Moreover, the devices also exhibited excellent spin Seebeck effects under a temperature gradient, which make the YN₂ monolayer a promising candidate for both spintronic and spin caloritronic applications. These peculiar spin transport properties were analyzed and explained from the calculated spin-resolved band structure and transmission spectrum based on first-principles combined with the non-equilibrium Green's function method.