J-V Kim

Understanding Nanoscale Temperature Gradients in Magnetic Nanocontacts

We have determined the temperature profile in magnetic nanocontacts under applied current densities typical of spin-torque oscillators (∼10(8)  A/cm2). The study combines experimental measurements of the electrical and magnetic properties of the nanocontacts and full three-dimensional simulations of the heat and current flow in these systems. It is found that the quadratic current-induced increase of the resistance due to Joule heating is independent of the applied temperature from 6 to 300 K. In terms of magnetization dynamics, the measured current-induced vortex nucleation, a thermally activated process, is found to be consistent with local temperatures increases of between 147 and 225 K. Simulations reproduce the experimental findings and show that significant thermal gradients exist out to 450 nm from the nanocontact.