We try to inject spins into nanoscale Si devices, a strongly valley splittied Si-2DEG, and thin layered materials. The nanoscale silicon devices have much space to investigate spin phenomena, such as a ballistic spin transport and a single spin tunneling. In particular, I am interested in nanoscale diluted magnetic semiconductors as a controllable spin injector.
Recently, reserches about thin layered materials are rapidly growing in spin-phenomena; [Gurram et al.][Avsar et al.], and so on. These materials have many attractive features and combinations. From the view point of spin injection, I am interested in tunneling anisotropic magnetoresistance(TAMR) between ferromagnets and transition metal dichalcogenides.
Under strong valley splitting, [Ghosh et al.] predicted that spin lifetime will be extremely modulated. Thereby, we aim to control spin lifetime, namely spin signal by the modulation of valley splitting in Si 2DEG. It can lead to a development of new-type of Si-based spin transistor.
In transition metal dichalcogenides, valley and spin state are strongly coupled. These can be polarized with magnetic fields, circularly polarized lights, strains, spin injections, and so on. Therefore, we can generate valley-spin polarization, artificially. I am intrested in edge states under valley-polarized states.
Film growth is one of the most important and fundamental technology for materials physics. By selecting elements, there are billions of combinations and posibilities. In these options, we will investigate about ferromagnet / semiconductor hetero-structures to improve spin injection efficiency and develop devices with spin and valley physics.
Recently, we have grown EuO on Si to obtain a perfect spin injector on Si. EuO has a spin polarization of 100%. However, its low curie temperature is the problem against a realization of spin devices at RT. Next, if possible, we will try multi-layered structures with ferromagnet oxides to increase curie temperature of this Eu chalcogenides.