Taking topological insulators for a spin: Towards understanding of spin and charge transport in Bi2Se3

Topological insulators are materials that host electrically conducting surface states in combination with an ideally insulating bulk. These surface states are robust due to the physical properties in the material that have analogies with the concept of ‘topology’ in mathematics. In the light of the research done in the group of Spintronics of Functional Materials, topological insulators are mainly interesting because of the special properties of the electron’s spin (a magnetic property that can only have two values). The spin orientation is coupled to the movement of electrons and therefore allows a good control over the spins. Such materials are thus suitable for spintronic applications, electronics that is based on the transport of the electron’s spin rather than the charge. The advantages of spintronics will lead to new, faster device schemes in information processing.

This thesis describes experiments that were done in order to get a better insight into spin and charge transport in topological insulators. An important point of consideration is the interaction between the normal bulk and the special surface states in these types of transport. In addition, the possible presence of many side effects originating from the material’s properties as well as experimental limitations yields that solely probing of one of the transport channels is impossible. Therefore, an extended analysis on the results is presented in this thesis where such possible side effects have been analyzed in detail. This thesis describes interesting as well as limiting factors of topological insulators to be used in future applications.