Charge-to-spin conversion efficiency in ferromagnetic nanowires by spin torque ferromagnetic resonance: Reconciling lineshape and linewidth analysis methods

Abstract

Spin orbit torques are of great interest for switching the magnetization direction in nanostructures, moving skyrmions and exciting spin waves. The standard method of determining their efficiency is by spin torque ferromagnetic resonance (ST-FMR), a technique that involves analyzing the resonance linewidth or lineshape. On microstuctures these two analysis methods are quite consistent. Here we present ST-FMR results on permalloy (Ni${}_{80}$Fe${}_{20}$) nanowires -- with widths varying from $150$ to 800 nm -- that show that the standard model used to analyze the resonance linewidth and lineshape give different results; the efficiency appears greatly enhanced in nanowires when the lineshape method is used. A ST-FMR model that properly accounts for the sample shape is presented and shows much better consistency between the two methods. Micromagnetic simulations are used to verify the model. These results and the more accurate nanowire model presented are of importance for characterizing and optimizing charge-to-spin conversion efficiencies in nanostructures.

7 pages, 6 figures

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Cited by in corpus (7)

• Maximizing Spin-Orbit Torque Generated by the Spin Hall Effect of Pt
• Spin-orbit torque characterization in a nutshell
• A Perspective on Electrical Generation of Spin Current for Magnetic Random Access Memories
• Efficient generation of out-of-plane polarized spin current in polycrystalline heavy metal devices with broken electric symmetries
• Resolving Discrepancies in Spin-Torque Ferromagnetic Resonance Measurements: Lineshape vs. Linewidth Analyses
• Voltage control of spin resonance in phase change materials
• Resonant Measurement of Non-Reorientable Spin-Orbit Torque from a Ferromagnetic Source Layer Accounting for Dynamic Spin Pumping