Spin-to-charge current interconversion in highly resistive sputtered bismuth selenide

Abstract

In this thesis, we characterize sputtered BiSe by several SCI techniques. Our first approach is one of the best known techniques, spin pumping. Chapter 4 presents the SCI results in sputtered BiSe by the spin pumping technique using opposite stacking orders (BiSe/Py and Py/BiSe). By studying the results on both systems, we found a strong interdiffusion, so that the chemical composition of the magnetic layers and the interfaces were not homogeneous, and therefore the models used to characterize the properties of the system were no longer valid. Ignoring these inhomogeneities in the interfaces and films would lead to an incorrect estimation of the SCI efficiency.In Chapter 5,we used a different configuration to performSCI measurements, with an architecture similar to the readout node of the (MESO) device, using T-shaped devices for local spin injection. Taking into account the knowledge gained in Chapter 4 (regarding interdiffusion), we fabricated local T-shaped devices and we were able to observe SCI in sputtered BiSe devices at room temperature and proved thatall parameters related to SCI efficiency, namely resistivity, ¿s and ¿SH, are affected by interdiffusion. In particular, the fact that a change in Se concentration by interdiffusion made a 6 times difference in resistivity.We have shown here how this can easily lead to an overestimation of the spin transport parameters.