Spin Dependent Transport Properties of Metallic and Semiconducting Nanostructures
Present day computing and communication devices rely on two different classes of technologies; information processing devices are based on electrical charge transport while information storage devices are based on orientation of electron spins in magnetic materials. Realization of a hybrid-type device based on charge as well as spin properties of electrons would perform both of these actions thereby enhancing computation power to many folds and reducing power consumptions. This dissertation focuses on the fabrication of such spin-devices based on metallic and semiconducting nanostructures. A simplified design of the spin-device consists of a spin injector, a semiconducting or a metallic channel, and a spin detector. The channel is the carrier of spin signal from the injector to the detector, and therefore plays a crucial role in the manipulation of spin properties in the device. In this work, nanostructures such as nanowires and nanostripes were used to function as the channel in the spin-device. Various physical and chemical methods were used to synthesize the nanostructures. Fabrication of the spin-devices from the nanostructures were carried out using two-stage electron beam lithography process. These spin-devices show large spin relaxation lengths compared to common materials such as copper and offer potential for novel future technologies. Further, nanowires of Co2FeAl and Cd1-xMnxTe were synthesized and studied their structural, magnetic and electrical transport properties to understand whether they can be used in spin-devices as spin injectors and spin detectors. In summary, the studies carried out in this thesis opens up several new material systems for future device applications.
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