Optical Exitation of Spin Currents in Heterotructures with Giant Spin-Orbit Coupling

The aim of this work is to study the magneto-optical Kerr Effect and the inverse spin Hall Effect in epitaxial ferrite-garnet ((YBi)3(FeAlSc)5012) / topological insulator (BiSbTeSe2) structures. Such structures are interesting because they can be used to implement spintronic devices that are promising for increasing energy efficiency and reducing losses during data transmission. Equatorial Kerr Effect and the inverse spin Hall Effect were obtained in this work as functions of the magnitude of the external magnetic field. The obtained relations for the equatorial Kerr Effect lead to the conclusion that saturation on the sample corresponds to an external magnetic field of 100 mT. In addition, the spin current generated in the garnet-ferrite layer reaches its maximum value when the external magnetic field is equal to the saturation field. During the study of the inverse spin Hall Effect, the behaviour of the relation between the optically induced voltage and the external magnetic field was revealed to be linear for one of the samples (the samples presented had the same layer of garnet-ferrite (4μ) and different thicknesses of the topological insulator). This behaviour could be explained by the fact that the classical Hall Effect suppresses the inverse spin Hall Effect due to its correlation with the thickness of the topological insulator. Moreover, the linear dependence of the induced voltage on the external magnetic field occurs in thicker layers of the topological insulator. The inverse spin Hall Effect can be observed in samples with a thick layer of a topological insulator at the ambient temperature of 20 K. Declining with ambient temperature the inverse spin Hall Effect becomes totally suppressed by the classical Effect at 50 K. Such behaviour occurs due lower resistance of the topological insulator at high temperatures thus the prevalence the charge current over the spin current.