Ultrafast Time-correlated Measurements of Spin-Seebeck effect in Yttrium Iron Garnet*

Recently, the time dependence of the spin-Seebeck effect (SSE) has been measured using optical pulses. These measurements suggest a time response faster than 5ns[1]. Here we present time-correlated measurements of the spin-Seebeck effect in Yttrium Iron Garnet (YIG) using an ultrafast laser. The pulsed beam is split into two individually modulated beams with a controllable delay time with sub-picosecond time resolution. The laser pulses are absorbed by a top Pt contact which generates a transient thermal gradient resulting in a spin current crossing the interface. The spin current is detected as a transverse voltage arising from the inverse spin Hall effect in Pt. We will present measurements of the time-correlated SSE signal from the two pulses as a function of delay time out to 1 ns. [1] Roschewsky et al., Appl. Phys. Lett.,~104,~ 202410 (2014).