Effect of GdIG interfacial layer on the spin pumping in YIG/Pt

We report on a growth-induced ∼2.5-nm-thick gadolinium iron garnet (GdIG) interfacial layer formed at the Y3Fe5O12 (YIG) film and Gd3Ga5O12 (GGG) substrate. The exchange coupling between the interfacial GdIG layer and the YIG layer results in an exchange-dominated nonpropagating spin wave (SW) mode aside from the uniform ferromagnetic resonance (FMR) mode observed in spin pumping measurements. The spin current generated by the SW mode is comparable to that generated by the uniform FMR mode. A theoretical model is provided to demonstrate that the exchange coupling between the interfacial GdIG layer and the YIG layer results in two resonance frequencies. Our results provide insights into the generation and propagation of spin currents in the YIG/Pt system for low-power spintronics.