Understanding nanoscale temperature gradients in magnetic nanocontacts

TL;DR

This study investigates the temperature distribution in magnetic nanocontacts under high current densities, revealing significant localized heating that impacts magnetization dynamics, with experimental and simulation approaches confirming temperature increases of around 160 K.

Contribution

The paper provides a combined experimental and simulation analysis of nanoscale temperature gradients in magnetic nanocontacts, highlighting the importance of current-induced heating in magnetization behavior.

Findings

Local temperature increase of about 160 K near the nanocontact

Heating extends approximately 450 nm from the contact

Heat sinking efficiency remains temperature-independent

Abstract

We determine the temperature profile in magnetic nanocontacts submitted to the very large current densities that are commonly used for spin-torque oscillator behavior. Experimentally, the quadratic current-induced increase of the resistance through Joule heating is independent of the applied temperature from 6 K to 300 K. The modeling of the experimental rate of the current-induced nucleation of a vortex under the nanocontact, assuming a thermally-activated process, is consistent with a local temperature increase between 150 K and 220 K. Simulations of heat generation and diffusion for the actual tridimensional geometry were conducted. They indicate a temperature-independent efficiency of the heat sinking from the electrodes, combined with a localized heating source arising from a nanocontact resistance that is also essentially temperature-independent. For practical currents, we conclude that the local increase of temperature is typically 160 K and it extends 450 nm about the nanocontact. Our findings imply that taking into account the current-induced heating at the nanoscale is essential for the understanding of magnetization dynamics in nanocontact systems.