Origin and transport signatures of spin-orbit interactions in one- and two-dimensional SrTiO3-based heterostructures

We study origin of Rashba spin-orbit interaction at SrTiO3 surfaces and LaAlO3/SrTiO3 interfaces by considering the interplay between atomic spin-orbit coupling and inversion asymmetry at the surface or interface. We show that in a simple tight-binding model involving 3d t(2g) bands of Ti ions, the induced spin-orbit coupling in the d(xz) and d(yz) bands is cubic in momentum whereas the spin-orbit interaction in the d(xy) band has linear momentum dependence. We also find that the spin-orbit interaction in one-dimensional channels at LaAlO3/SrTiO3 interfaces is linear in momentum for all bands. We discuss implications of our results for transport experiments on SrTiO3 surfaces and LaAlO3/SrTiO3 interfaces. In particular, we analyze the effect of a given spin-orbit interaction term on magnetotransport of LaAlO3/SrTiO3 by calculating weak antilocalization corrections to the conductance and to universal conductance fluctuations.