Temperature dependent spin dynamics in La$_{0.67}$Sr$_{0.33}$MnO$_3$/Pt bilayers

Abstract

Complex ferromagnetic oxides such as La$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) offer pathways for creating energy efficient spintronic devices with new functionalities. LSMO exhibits high-temperature ferromagnetism, half metallicity, sharp resonance linewidth, low damping and a large anisotropic magnetoresistance response. Combined with Pt, a proven material with high spin-charge conversion efficiency, LSMO can be used to create robust nano-oscillators for neuromorphic computing. Ferromagnetic resonance (FMR) and device level spin-pumping FMR measurements are performed to investigate the magnetization dynamics and spin transport in NdGaO3(110)/LSMO(15 nm)/Pt(0 and 5 nm) thin films ranging from 300K to 90K and compare the device performance with Py(7 nm)/Pt(5 nm) sample. The spin current pumped into Pt is quantified to determine the temperature dependent influence of interfacial interactions. The generated spin current in the micro-device is maximum at 170K for the optimally grown LSMO/Pt films. Additionally, this bilayer system exhibits low magnetic Gilbert damping (0.002), small linewidth (12 Oe) and a large spin Hall angle ($\approx$ 3.2%) at 170K. By fine-tuning the LSMO/Pt interface quality and integrating it into the device structure, the system exhibits a fourfold enhancement in signal output for LSMO/Pt devices compared to the Pt/Py system. Such robust device level performance can pave way for energy-efficient spintronic based devices.