Controlling Kondo-like Scattering at the SrTiO(3)-based Interfaces

The observation of magnetic interaction at the interface between nonmagnetic oxides has attracted much attention in recent years. In this report, we show that the Kondo-like scattering at the SrTiO(3)-based conducting interface is enhanced by increasing the lattice mismatch and growth oxygen pressure P(O2). For the 26-unit-cell LaAlO(3)/SrTiO(3) (LAO/STO) interface with lattice mismatch being 3.0%, the Kondo-like scattering is observed when P(O2) is beyond 1 mTorr. By contrast, when the lattice mismatch is reduced to 1.0% at the (La(0.3)Sr(0.7))(Al(0.65)Ta(0.35))O(3)/SrTiO(3) (LSAT/STO) interface, the metallic state is always preserved up to P(O2) of 100 mTorr. The data from Hall measurement and X-ray absorption near edge structure (XANES) spectroscopy reveal that the larger amount of localized Ti(3+) ions are formed at the LAO/STO interface compared to LSAT/STO. Those localized Ti(3+) ions with unpaired electrons can be spin-polarized to scatter mobile electrons, responsible for the Kondo-like scattering observed at the LAO/STO interface.