Magneto- and thermo- electric spin currents in doped and disordered spintronic materials

Spin electronics, more commonly known as spintronics, is an expanding field that is used not just to exploit the charge of electrons but also their intrinsic spin to store and manipulate information in devices.

Common electronics rely on the charge of these electrons to encode information, leading to significant energy dissipation, especially at high processing speeds. By leveraging the spin of electrons, which can be manipulated without necessarily moving these charge carriers. Magneto- and thermoelectric effects provide ways to be able to control and generate spin currents, which offers the prospect of developing much better devices. Disordered materials can affect spintronic performance; the disorder in these materials can cause changes in the electrons and their spins, affecting the transport properties. Within doped materials, it allows the controlled addition of dopants into spintronic materials to tune the properties for desirable outcomes. Both these materials could be used to possibly enhance the magneto- and thermoelectric effects, ideal for spintronics. The main magneto- and thermoelectric effects studied and discussed in this thesis are the anomalous Hall effect, the anomalous Nernst effect and the spin Hall effect.

In this thesis, we present the electronic and structural properties to determine how the magneto- and thermoelectric effects change due to the disordering of the spintronic material Co2MnSi and doping of copper with tantalum by using density functional theory to model the contributions to these effects.

First, we shall discuss the different magneto- and thermoelectric effects present within this study and the contributions that arise within them. There are two main contributions outlined in this thesis: The intrinsic effect due to the nature of the material itself and the extrinsic effect arising from scatterers within these materials. In our investigation, we show the electronic properties of the material within the ordered and disordered phase of Co2MnSi and how it affects the anomalous Hall and Nernst effects, and then we have compared this to experimental work done. We also investigated different methods of adding various levels of dopant to Cu and how this contributes to the spin Hall effect.