Non-local spin transport measurement in TbIG thin films grown by pulsed laser deposition*

Ferrimagnetic insulators (FMIs) attract a lot of attention in spintronics recently. As a medium, FMIs support pure spin current carried by magnon transport over a relatively long distance. In this work, we use nonlocal method to probe spin transport in terbium iron garnet (Tb₃Fe₅O₁₂ or TbIG). We obtain high-quality epitaxial TbIG thin films on the substrates of GGG(111) using a PLD system. After 750 degree Celsius post-growth rapid thermal annealing, clear RHEED patterns demonstrate the single crystal quality of TbIG films, which is further confirmed by X-ray diffraction and atomic force microscopy results. The non-local signal has a sign reversal at 270 K, which corresponds to the compensation temperature of TbIG. Below the compensation temperature, the non-local signal stays approximately constant until a dramatic increase sets in at 50 K, which persists to the lowest temperature of 2 K. We attribute this rapid increase to the spin current transport associated with paramagnetic Tb-spins. We also discuss the temperature dependence of the nonlocal signal in garnets with and without rare-earth moments.