Ferromagnetic Resonance of a [GeTe/Sb2Te3]6/Py Superlattice

A [GeTe/Sb2Te3] superlattice is known as a topological insulator. It shows magnetic responses such as magneto-optical effect, magneto resistance, magneto capacitance, and so on. We have reported that [GeTe/Sb2Te3] superlattice film has a large spin-orbit interaction using a spin pumping method of a [GeTe/Sb2Te3]/Py superlattice. In this paper, we demonstrate a ST-FMR (spin transfer torque ferromagnetic resonance) of the [GeTe/Sb2Te3](6)/Py superlattice, compared with a W/Py bilayer. The superlattice film showed a large resonance signal with a symmetric component. The ratio of symmetric components (S) to anti-symmetric (A) components (S/A) was 1.4, which suggests that the superlattice exhibits a large spin Hall angle. The [GeTe/Sb2Te3] superlattice will be suitable as a hetero-interface material required for high performance spintronics devices in future.