Hot-electron dynamics in oxide heterostructures

The behavior of hot electrons has potential to provide useful insight in the dynamics of strongly correlated electron systems, but it is inherently challenging as an experimental probe due to rapid relaxation (typically on the order of femtoseconds) within very short length scales (typically few nanometers). The hot-electron transistor (HET) provides a unique measurement geometry for this purpose, where the (correlated) metal base can be studied by vertically setting the transport length scale comparable to the hot-electron mean free path. Here we use the HET to probe the evolution of vertical hot-electron transport across oxide heterostructures with a metallic SrRuO₃ (SRO) base, well-known for ‘badly metallic’ behavior as a consequence of intermediate electron-correlations. We observe an abrupt increase of the hot-electron mean free path as a function of decreasing temperature at the ferromagnetic transition. Furthermore, we present results on the anisotropic scattering of hot-electrons as a function of the magnetization orientation deep in the ferromagnetic state.