Epitaxial Thin Films*

ABO₃ perovskite metal oxides, where A represents an alkaline earth metal, B is a transition metal, and O is oxygen exhibit are scientifically interesting and technologically important for many applications. Calcium manganese oxide (CaMnO₃, abbreviated as CMO) is a member of the perovskite family that has attracted attention for renewable energy applications. Electrical resistivity, a key property for such applications, can be controlled by introducing vacancies at the oxygen sites within the crystal lattice, which occur when the material is oxygen-deficient. In this study, we present recent findings on controlling oxygen deficiency in epitaxial thin films of CMO, grown using pulsed laser deposition (PLD). Following up on our previous research, which has shown that substrate-induced tensile strain helps stabilize oxygen deficiency, we have investigated the effects of varying the growth oxygen pressure and the incident laser fluence on the properties of CMO films on two substrates, (100) oriented LaAlO₃ (LAO) and (100) oriented SrTiO₃ (STO) which have different degrees of lattice mismatch with CMO. We grew films of varying thickness on both substrates under selected combinations of laser fluence and growth oxygen pressure. We will present structural, electrical and magneto-transport properties of these films and discuss how the results help us to optimize the combined parameter space for modulating the electrical conductivity.