Electric field modulation of spin and charge transport in two dimensional materials and complex oxide hybrids

Electronics work on the basis of the charge of an electron. Electrons also have another property called spin, which can either rotate clockwise or counterclockwise. With this property we can transport information, because we can couple a 0 or 1 to these rotational directions. In practice however, the use of the electron spin is difficult, because the spin is usually randomized after a short while. The origin of this is not clear.
In this thesis we investigate what can influence a spin.

First we investigate spin transport in graphene, because in theory spins can be transported across large distances in graphene. However, in practice this is not the case. The origin of this discrepancy is not clear. In order to investigate this, we placed graphene on a substrate which reduces influences of electric fields from contamination. We did not find an improvement of the spin relaxation length. This provides us a clue that these fields are probably not playing a dominant role in spin relaxation.

Secondly we investigated an alternative material which can be used as a barrier between graphene and magnetic contacts. The magnetic contacts are used to inject spins into graphene. From our measurements it is apparent that this material shows the right behavior to be used as a barrier.

Lastly we also looked how we can vary the size of the spin signal. We injected electron spins into a semiconductor and saw that we could influence the measured spin signal by applying a voltage.