Spin Seebeck effect in Vanadium Tetracyanoethylene

Vanadium tetracyanoethylene (V(TCNE)_x, x~2) is an organic based ferrimagnetic coordination compound, with extremely low Gilbert damping which is comparable to yttrium iron garnet. Due to its non-crystalline nature, it is interesting to investigate how spin waves propagate in the material. One possible way is through thermally driven spin pumping, namely spin Seebeck effect (SSE). Here, we present a systematic study on the temperature and thickness dependence of SSE in V(TCNE)_x. The thin films (thickness on the order of 100 nm) are grown via chemical vapor deposition on a platinum layer on sapphire substrate. By applying a temperature gradient perpendicular to the V(TCNE)_x/Pt, a large SSE signal is collected. Further analysis on the temperature and thickness dependence helps us understand the length scales of the propagation of spin waves.