Direct-Current Induced Dynamics in Co90Fe10/Ni80Fe20 Point Contacts

TL;DR

This paper demonstrates a method to induce and tune high-frequency magnetization dynamics in ferromagnetic point contacts using spin-polarized DC currents, achieving broad frequency ranges and high quality factors.

Contribution

It introduces a novel approach for controlling ferromagnetic dynamics with direct current, enabling wide frequency tuning and high oscillation quality in point contact devices.

Findings

Frequency tuning from below 5 GHz to above 40 GHz

Oscillation quality factors between 200 and 800

Agreement with single-domain simulation results

Abstract

We have directly measured coherent high-frequency magnetization dynamics in ferromagnet films induced by a spin-polarized DC current. The precession frequency can be tuned over a range of several gigahertz, by varying the applied current. The frequencies of excitation also vary with applied field, resulting in a microwave oscillator that can be tuned from below 5 GHz to above 40 GHz. This novel method of inducing high-frequency dynamics yields oscillations having quality factors from 200 to 800. We compare our results with those from single-domain simulations of current-induced dynamics.