Anisotropic magnetoresistance and negative magnetoresistance for in-plane fields are compared for the LaAlO 3/SrTiO 3 interface and the symmetric Nb-doped SrTiO 3 heterostructure. Both effects are exceptionally strong in LaAlO 3/SrTiO 3. We analyze their temperature, magnetic field, and gate voltage dependencies and find them to arise from a Rashba-type spin-orbit coupling with magnetic scatterers that have two contributions to their potential: spin exchange and Coulomb interaction. Atomic spin-orbit coupling is sufficient to explain the small effects observed in Nb-doped SrTiO 3. These results clarify contradicting transport interpretations in SrTiO 3 based heterostructures.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 11 Sep 2012|