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, Ag connecting wire, and detector. An analytical model explained diffusion over measured temperature range (2--300 K) injector-detector separation (400--3000 nm). The characteristic lengths Peltier Joule heat differ remarkably below 60 K, fact that can be by onset ballistic phonon transfer substrate.