Correlation transports at p-/n-types in electron metastable perovskite family of rare-earth nickelates

Abstract

It is important to achieve both donor and acceptor doping for correlated oxide semiconductors to cater for elementary device constructions, e.g., establishing a p-n junction and a thermal couple or a thermoelectric π-joint in correlated electronics. The perovskite family of rare-earth nickelates (ReNiO3) exhibits correlated transportation characters (e.g., metal to insulator transitions and thermistor transportations) dominated by electron conductions, as indicated by their negative thermopower for n-type materials. Herein, we demonstrate the presence of positive magnitude of thermopower as achieved in GdNiO3 single crystalline thin films, indicating a hole dominated transportation for p-type correlated semiconductors. Probing the Ni-L edge of GdNiO3 via near edge x-ray absorption fine structure indicates its distinguished intermediate acceptor energy states that are more easily occupied by the thermal excited valence band electrons. The hole-dominated transportation for GdNiO3 was further confirmed by its increased localization length and opposite sign in magnetoresistance, which are derived from the general tendency of ReNiO3, owing to the larger effective mass of holes compared to electrons. The discovery of p-types in GdNiO3 will further promote establishing ReNiO3-based elementary semiconductive devices in the field of correlated electronics.