Tunable Enhancement of Magnetization Dynamics by Crystal Cut at Interface Exchange Coupled $\alpha$-Fe$_2$O$_3$/NiFe Heterostructures

TL;DR

This study demonstrates how crystal orientation, temperature, and magnetic fields can dynamically tune ferromagnetic resonance in $ ext{Fe}_2 ext{O}_3$/NiFe heterostructures, advancing spintronic device control.

Contribution

It reveals a novel, in-situ method to modulate FMR via interfacial exchange coupling controlled by crystal cut and temperature in AFM/FM heterostructures.

Findings

FMR frequency can be significantly modulated by Nél vector configuration.

Distinct resonance behaviors observed for different crystal orientations.

Theoretical models confirm the dependence of coupling on magnetic alignment.

Abstract

We investigate spin dynamics in $\alpha$-Fe$_{2}$O$_{3}$/Ni$_{80}$Fe$_{20}$ (Py) heterostructures, uncovering a robust mechanism for in-situ modulation of ferromagnetic resonance (FMR) through precise control of temperature, applied magnetic field and crystal orientation. Employing cryogenic ferromagnetic resonance spectroscopy, we demonstrate that the interfacial coupling between the N\'eel vector of $\alpha$-Fe$_{2}$O$_{3}$ and the magnetization of the Py layer is highly tunable across the Morin transition temperature $(T_M)$. Our experiments reveal distinct resonance behavior for different crystal orientations, highlighting the pivotal role of exchange coupling strength in dictating FMR frequencies. Theoretical modeling corroborates the experimental findings, elucidating the dependence of coupling on the relative alignment of the N\'eel vector and ferromagnetic magnetization. Notably, we achieve significant modulation of FMR frequencies by manipulating the N\'eel vector configuration, facilitated by temperature variations, applied magnetic fields and crystal orientation adjustments. These advancements demonstrate the potential for dynamic control of spin interactions in AFM/FM heterostructures, paving the way for the development of advanced spintronic devices with tunable magnetic properties. Our work provides critical insights into the fundamental interactions governing hybrid spin systems and opens new avenues for the design of versatile, temperature-responsive magnetoelectronic applications.