Abstract:
Electrons have a quantum state of spin as well as electric charges. Spintronics or spin electronics is known as an emergent technology which exploits the quantum state of electron spin in addition to electron charges. In order to make a spintronic device out of non-magnetic materials, the primary requirement is to have a system that can generate a flow of spin polarized electrons, and a system that is sensitive to the spin polarization of electrons. This thesis focuses on the experimental approach towards spin current generation, detection and manipulation in III-V non-magnetic semiconductors.
We reports the observation of spin current generation by linearly polarized optical excitation via interband transition and the consequent electric current under the presence of in-plane magnetic field. We attribute the phenomena to the asymmetric interband optical pumping under spin-orbit coupling. The experiment data is well explained by the proposed microscopic model based on spin dependent interband photoexcitation.
The knowledge of electron g factor is essential for spin manipulation. While there exist technical difficulties in determining the sign of g factor in semiconductors by the established magneto-optical spectroscopic methods. We developed two methods utilizing the time-resolved Kerr rotation spectroscopy to determine both the magnitude and the sign of the g factor in various semiconductor structures: GaAs thin film, GaAs two dimensional electron gas (2DEG) and GaNAs/GaAs quantum wells(QW). The g factor study shows a strong dependence on the weight of N component. It offers a potential method to engineer the g factor in GaAs semiconductor devices.