Probing anisotropy in epitaxial Fe/Pt bilayers by spin-orbit torque ferromagnetic resonance

TL;DR

This paper demonstrates the use of spin-orbit torque ferromagnetic resonance (STFMR) to probe magnetic anisotropies in epitaxial Fe/Pt bilayers, providing a simple method for analyzing magnetic properties in microstructures.

Contribution

It introduces STFMR as an effective technique to investigate magnetic anisotropies in epitaxial Fe/Pt bilayers, validated by experimental and micromagnetic modeling.

Findings

STFMR reveals strong magnetic anisotropy in Fe/Pt bilayers.

Comparison with broadband FMR validates STFMR as a probing method.

Analytical and micromagnetic models explain field-dependent magnetization.

Abstract

We report the generation and detection of spin-orbit torque ferromagnetic resonance (STFMR) in micropatterned epitaxial Fe/Pt bilayers grown by molecular beam epitaxy. The magnetic field dependent measurements at an in-plane magnetic field angle of 45 degrees with respect to the microwave-current direction reveal the presence of two distinct voltage peaks indicative of a strong magnetic anisotropy. We show that STFMR can be employed to probe the underlying magnetic properties including the anisotropies in the Fe layer. We compare our STFMR results with broadband ferromagnetic resonance spectroscopy of the unpatterned bilayer thin films. The experimental STFMR measurements are interpreted using an analytical formalism and further confirmed using micromagnetic modeling, which shed light on the field-dependent magnetization alignment in the microstructures responsible for the STFMR rectification. Our results demonstrate a simple and efficient method for determining magnetic anisotropies in microstructures by means of rf spectroscopy.