Understanding nanoscale temperature gradients in magnetic nanocontacts

• Published in: arXiv.org 2012-06
• Main Authors: Petit-Watelot, Sébastien, Ruben Miguel Otxoa, Manfrini, Mauricio, Wim Van Roy, Lagae, Liesbet, Joo-Von, Kim, Devolder, Thibaut
• Format: Article
• Language: English
• Subjects: Computer simulation; Heat generation; Nucleation; Ohmic dissipation; Resistance heating; Temperature gradients; Temperature profiles
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1206.5680

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.