# Magnetic proximity effect induced FMR frequency enhancement in {Py/FeMn} bilayers

## TL;DR

This study demonstrates a significant enhancement of ferromagnetic resonance frequency in Py/FeMn bilayers due to magnetic proximity effects, potentially enabling high-speed spintronic devices by bridging the GHz-THz gap.

## Contribution

It reveals a large FMR frequency increase in Py/FeMn bilayers caused by magnetic proximity effects in ultrathin FeMn, advancing understanding of FM/AFM interactions.

## Key findings

- FMR frequency reaches sub-THz range in Py/FeMn bilayers.
- Magnetic proximity effect induces sizable magnetic moments in FeMn.
- Potential for high-speed spintronic applications by bridging GHz-THz gap.

## Abstract

Ferromagnetic resonance (FMR) in exchange-coupled ferromagnet-antiferromagnet (FM/AFM) bilayers commonly shows a moderate increase in the resonance frequency owing to the induced unidirectional anisotropy. Here we report a large FMR frequency enhancement toward the sub-THz range observed in Py/FeMn with ultrathin AFM FeMn. The effect is connected with a sizable induced magnetic moment in FeMn caused by the magnetic proximity effect from the Py layer. The observed FMR properties are explained as due to the competing intrinsic antiferromagnetic order and the ferromagnetic proximity effect in nanometer thin FeMn. Our results show that combining materials with strong and weak anti/ferromagnetic ordering can potentially close the notoriously difficult GHz-THz gap important for high-speed spintronic applications.