Anomalous Electron Conduction of Nd_0.6Sr_0.4FeO_3-δ Thin Film with Lattice Distortion and Oxygen Vacancies

Abstract

The structural and electrical properties of Nd_0.6Sr_0.4FeO_3-δ (NSFO) have been investigated in the bulk ceramic and thin film forms. Although NSFO bulk ceramic exhibits p-type conduction, the NSFO thin film changes to n-type conduction. The NSFO thin film has larger lattice distortion than the bulk ceramic due to the lattice mismatch between NSFO and Al₂O₃ substrate. The low crystal symmetry of the thin film is reflected in the electronic structure measured by soft-X-ray spectroscopy. The electrical conductivity of the NSFO thin film with 112 nm thickness is higher than that of the bulk ceramic at above 850 K. This originates from the change of electron number for e_g-subband in the Fe 3d valence band with the lattice distortion.