Physical Review Letters
Scanning Thermal Microscopy and Ballistic Phonon Transport in Lateral Spin Valves
Using scanning thermal microscopy, we have mapped the spatial distribution of temperatures in an operating nanoscale device formed from a magnetic injector, an Ag connecting wire, and a magnetic detector. An analytical model explained the thermal diffusion over the measured temperature range (2-300 K) and injector-detector separation (400-3000 nm). The characteristic diffusion lengths of the Peltier and Joule heat differ remarkably below 60 K, a fact that can be explained by the onset of ballistic phonon heat transfer in the substrate.