Effect of oxygen content on the magnetoresistance of Pt/NiFe2O4 heterostructures

Abstract

Abstract The magnetoresistance of heavy metal and magnetic insulator heterostructures is mainly controlled by changing the thickness or the composition of the heavy metals, limiting the magnetoresistance properties in a single device. In this work, we changed the interfacial magnetization of ferrimagnetic NiFe2O4 (NFO) by controlling the oxygen content of NFO film. With increasing of the oxygen partial pressure during pulsed laser deposition, the magnetization of NFO and the spin-Hall magnetoresistance of the Pt/NFO increase. The valence states of Ni and Fe also increase accordingly, which can be revealed by X-ray photoelectron spectroscopy. The magnetization strength of Pt caused by the interfacial magnetization intensity of NFO film can effectively adjust weak localization and weak antilocalization below 50 K, which in turn affects the sign and value of the magnetoresistance. Our work paves the way for the manipulation of the magnetoresistance of heavy metal and magnetic insulator heterostructure devices.