# High frequency voltage-induced ferromagnetic resonance in magnetic tunnel junctions

## TL;DR

This paper investigates voltage-induced ferromagnetic resonance in magnetic tunnel junctions with a tungsten buffer, demonstrating control over magnetic properties and achieving resonance frequencies above 30 GHz through optimized structures.

## Contribution

It introduces an optimized MTJ structure enabling high-frequency V-FMR and combines experimental analysis with macrospin modeling for detailed magnetic property characterization.

## Key findings

- V-FMR observed at frequencies over 30 GHz
- PMA energy controlled by layer thickness and annealing
- Magnetization damping characterized through modeling

## Abstract

Voltage-induced ferromagnetic resonance (V-FMR) in magnetic tunnel junctions (MTJs) with a W buffer is investigated. Perpendicular magnetic anisotropy (PMA) energy is controlled by both thickness of a CoFeB free layer deposited directly on the W buffer and a post-annealing process at different temperatures. The PMA energy as well as the magnetization damping are determined by analysing field-dependent FMR signals in different field geometries. An optimized MTJ structure enabled excitation of V-FMR at frequencies exceeding 30 GHz. The macrospin modelling is used to analyse the field- and angular-dependence of the V-FMR signal and to support experimental magnetization damping extraction.