Single spin-polarized Fermi surface in SrTiO3 thin films

The 2D electron gas (2DEG) formed at the surface of SrTiO3(001) has attracted great interest because of its fascinating physical properties and potential as a novel electronic platform, but up to now has eluded a comprehensible way to tune its properties. Using angle-resolved photoemission spectroscopy with and without spin detection, we here show that the band filling can be controlled by growing thin SrTiO3 films on Nb-doped SrTiO3(001) substrates. This results in a single spin-polarized 2D Fermi surface, which bears potential as a platform for Majorana physics. Based on our results, it can furthermore be concluded that the 2DEG does not extend more than two unit cells into the film and that its properties depend on the amount of SrOx at the surface and possibly the dielectric response of the system.