Low-temperature nanoscale heat transport in a gadolinium iron garnet heterostructure probed by ultrafast x-ray diffraction.

Time-resolved x-ray diffraction has been used to measure the low-temperature thermal transport properties of a Pt/GdFeO//GdGaO metal/oxide heterostructure relevant to applications in spin caloritronics. A pulsed femtosecond optical signal produces a rapid temperature rise in the Pt layer, followed by heat transport into the GdFeO (GdIG) thin film and the GdGaO (GGG) substrate. The time dependence of x-ray diffraction from the GdIG layer was tracked using an accelerator-based femtosecond x-ray source.