Correlated Electron Metals with High Entropy: Thin Film Growth and Properties

Novel conducting complex oxides with high electron correlation are of keen interest for UV-transparent applications, and as hosts for fundamental studies of correlated electron systems and spin-hall effect. Sr based cubic perovskite oxides are appealing to explore due to their heavy cation solubility and tunable electrical conductivity and transparency. Utilizing a high configurational entropy formulation, the high symmetry perovskite phase can be stabilized with five cations on the perovskite B-site. Our results show that Sr_x(Ti,Nb,Cr,Mo,W)O₃ thin films grown by pulsed laser deposition are stabilized as single-phase perovskite. Derivative systems with four B-cations instead of five, exhibit chemical and/or phase segregation. Contributions from individual B-cations and their interactions result in unique overall transport properties. For instance, Cr markedly influences electrical transport. A-site vacancies and doping, too, influence electronic and optical properties, and structure stability. The experimental findings are supported by first principles calculations that highlight the cation coexistance effect on octahedral tilting, tolerance factor, band structure and orbital filling.