Investigation of the thermal tolerance of silicon-based lateral spin valves

Abstract

Improvement in the thermal tolerance of Si-based spin devices is realized by employing thermally stable nonmagnetic (NM) electrodes. For Au/Ta/Al electrodes, intermixing between Al atoms and Au atoms occurs at approximately 300 °C, resulting in the formation of a Au/Si interface. The Au–Si liquid phase is formed and diffuses mainly along an in-plane direction between the Si and AlN capping layers, eventually breaking the MgO layer of the ferromagnetic (FM) metal/MgO electrodes, which is located 7 µm away from the NM electrodes. By changing the layer structure of the NM electrode from Au/Ta/Al to Au/Ta, the thermal tolerance is clearly enhanced. Clear spin transport signals are obtained even after annealing at 400 °C. To investigate the effects of Mg insertion in FM electrodes on thermal tolerance, we also compare the thermal tolerance among Fe/Co/MgO, Fe/Co/Mg/MgO and Fe/Co/MgO/Mg contacts. Although a highly efficient spin injection has been reported by insertion of a thin Mg layer below or above the MgO layer, these thermal tolerances decrease obviously.

Research on Spintronic Functions of Non-Metallic Materials and Its Modulation by External Fields

“…13) 81) . In the course of these significant studies, a number of detailed spintronic physics in Si were clarified: spin drift in Si 82,83) , bias voltage dependence of spin signals 84) , clarification of the origin the "inverted Hanle" effect 85) , enhancement of spin signals by utilizing spin drift and clarification of its underlying physics [86][87][88] , achievement of thermal spin injection in Si 89) , investigation of gating effects on spin signals 90) , and thermal annealing effects on spin signals 91,92) . Notable achievements in Si spintronics from application-oriented viewpoints are pin current and spin transport in a highly doped Si channel at room temperature (RT) using a etector consisting of an Fe/MgO tunnel barrier.…”