Spin Hall magnetoresistance in paramagnetic NdGaO3

TL;DR

This study demonstrates the use of spin Hall magnetoresistance (SMR) to probe paramagnetic NdGaO3, revealing its potential for spin transport despite lacking spontaneous magnetization, through extensive temperature and angle-dependent measurements.

Contribution

It introduces SMR as an effective tool for studying paramagnetic materials like NdGaO3, expanding its application beyond ordered magnetic systems.

Findings

SMR observed in Pt/NdGaO3 bilayer correlates with magnetization.

ADMR response shows linear bias dependence, characteristic of SMR.

Control experiments confirm the SMR origin in the bilayer system.

Abstract

In recent years, spin Hall magnetoresistance (SMR) has emerged as an efficient way to probe the spontaneous magnetization state in ordered magnetic systems, by electrical current. Less known is its versatility as a probe of materials that do not possess spontaneous magnetization such as in paramagnets. In this work, SMR is used to probe paramagnetic NdGaO3 (NGO), a rare earth oxide, possessing a sizable spin orbit interaction (L=6). NGO has not been investigated earlier for its efficiency in propagating spins. We have performed extensive temperature and angle dependent-magnetoresistance (ADMR) studies along dissimilar crystallographic axes in NGO, using platinum (Pt) as spin injector and detector and utilizing (inverse) spin Hall effect. We find a close correlation between the temperature dependence of the ADMR response with magnetization in NGO and a linear current bias dependence of the ADMR amplitudes. These are chacteristics of SMR effect in Pt/NGO, arising from the torque acting on localized moments in NGO and considering crystal field induced intermultiplet transitions with temperature. Control experiments on Pt/SrTiO3 and Pt/SiO2 devices were also carried out in order to validate the observed SMR response in Pt/NGO bilayer and to rule out magnetoresistive contributions from Pt.