Designing a fully compensated half-metallic ferrimagnet

Recent experimental work on Mn2Rux Ga 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 Mn2Rux Ga 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.