Structural, electronic and magnetic properties of Fe-doped strontium ruthenates

By employing a combined approach of density-functional theory (DFT) and dynamical mean-field theory (DMFT) calculations, we examine the structural, electronic, and magnetic characteristics of two distinct strontium ruthenates: Sr2RuO4, an unconventional superconductor, and the correlated metal SrRuO3, both at 50% Fe-doping level. In both Sr2Fe0.5Ru0.5O4 and SrFe0.5Ru0.5O3, the original ruthenium (Ru) and the dopant iron (Fe) atoms adopt 3-dimensional and 2-dimensional G-type structures, respectively. The hybridization between Fe-3d and Ru-4d is comparatively weaker than in other double perovskite systems. The interplay between strong correlations and reduced itinerancy results in significant spin splitting at Fe and Ru sites. Consequently, a charge transfer process, along with the super-exchange effect, leads to antiferromagnetically coupled Fe3+ and Ru5+ ions and establishes a semiconducting ferrimagnetic order. Subsequent DMFT calculations demonstrate the persistence of the ferrimagnetic order even at room temperature (300 K). These findings align with prior reports on SrFe0.5Ru0.5O3, thus reinforcing the notion that 3d-4d transition metal oxides hold considerable promise as candidates for high-performance spintronic devices, such as spin-valve sensors and spintronic giant magnetoresistance devices.