Designing a fully compensated half-metallic ferrimagnet

Recent experimental work on Mn₂RuₓGa demonstrates its potential as a compensated ferrimagnetic half metal (CFHM). Here we present a set of high-throughput ab initio density functional theory calculations and a detailed experimental characterization that enable us to correctly describe the nominal Mn₂RuₓGa thin films, in particular, with regard to site disorder and defects. We then construct models that accurately capture all the key features of the Mn-Ru-Ga system, including magnetic compensation and the spin gap at the Fermi level. We find that electronic doping is necessary, which is achieved with a Mn/Ga ratio smaller than two. Our study shows how composition and substrate-induced biaxial strain can be combined to design a ferrimagnetic half metal with a compensation point close to room temperature.