Injection, transport and manipulation of pure spin currents in metallic lateral spin valves

Résumé

ABSTRACT OF THE PHD THESISThe work realized throughout this thesis is based on the use of lateral spin valves (LSV), which consist of two ferromagnetic (FM) electrodes, bridged by a non-magnetic (NM) cannel. Thanks to their non-local geometry, they provide a way of creating pure spin currents. The fact that such currents are completely decoupled from the charge, avoiding any spurious effect, makes LSVs an effective for the obtention of spin-injection properties of a FM/NM system, as well as spin-transport properties of a NM metal. In the first part of the thesis, Co/Cu and Py/Cu LSVs are used in order to carry out a basic study about spin-injection and spin-transport properties. With that purpose the spin polarization of Py and Co are obtained and compared as a function of temperature. In addition, the spin-diffusion length of Cu is obtained as a function of temperature and of the different dimensions of the Cu cannel.The second part of the thesis is based on the manipulation of the pure spin currents. First of all, the already known Hanle effect is analized in LSVs with different FM/NM interface resistances. Furthermore, a novel manner of spin manipulation is proposed, based on the interaction between the spins and the magnetization of a FM insulator (FMI) substrate, which is controlled by applying small magnetic field. We develop a theory for explaining such manipulation, which is proven by our experiments.