# Chaos in Magnetic Nanocontact Vortex Oscillators

## TL;DR

This paper experimentally investigates chaotic vortex oscillations in magnetic nanocontacts driven by spin-torque, revealing complex modulation behaviors including incommensurate states and devil's staircases, supported by advanced time-series analysis.

## Contribution

It provides the first experimental evidence of chaos in vortex oscillations within magnetic nanocontacts, confirming theoretical predictions.

## Key findings

- Identification of modulation by relaxation oscillations above current threshold
- Observation of commensurate and incommensurate states with devil's staircases
- Experimental confirmation of chaos in vortex oscillations

## Abstract

We present an experimental study of spin-torque driven vortex self-oscillations in magnetic nanocontacts. We find that above a certain threshold in applied currents, the vortex gyration around the nanocontact is modulated by relaxation oscillations, which involve periodic reversals of the vortex core. This modulation leads to the appearance of commensurate but also more interestingly here, incommensurate states, which are characterized by devil's staircases in the modulation frequency. We use frequency- and time-domain measurements together with advanced time-series analyses to provide experimental evidence of chaos in incommensurate states of vortex oscillations, in agreement with theoretical predictions.