Unveiling the mechanism of spin to charge conversion in the ferroelectric topological crystalline insulator SnTe

The ferroelectric topological crystalline insulator SnTe is a promising material for ferronics and spintronics studies and applications because of the strong spin-orbit coupling and surface states protected by the mirror symmetry of the crystal. In this paper, we report ferromagnetic resonance-driven spin-pumping experiments in several bilayers and trilayers having one layer of SnTe with thickness varying in the range 3--30 nm and different ferromagnetic layers used to inject the spin-pumped spin current. In all samples x-ray-diffraction spectra strongly indicate that the SnTe films grown are topological crystalline insulators and consequently have preserved topological surface states. The spin-pumping studies reveal that the dominant spin to charge conversion mechanism in SnTe is the inverse Rashba-Edelstein effect (IREE), evidencing that the topological surface states are preserved. From the data in all samples, we obtain for the IREE parameter values in the range 1.1--2.8 pm, which are comparable to the ones measured in graphene, Bi₂Se₃, and others topological insulators.