  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 SrTiO3-based conducting interface is
enhanced by increasing the lattice mismatch and growth oxygen pressure PO2. For
the 26-unit-cell LaAlO3/SrTiO3 (LAO/STO) interface with lattice mismatch being
3.0%, the Kondo-like scattering is observed when PO2 is beyond 1 mTorr. By
contrast, when the lattice mismatch is reduced to 1.0% at the
(La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) interface, the metallic state is
always preserved up to PO2 of 100 mTorr. The data from Hall measurement and
X-ray absorption near edge structure (XANES) spectroscopy reveal that the
larger amount of localized Ti3+ ions are formed at the LAO/STO interface
compared to LSAT/STO. Those localized Ti3+ ions with unpaired electrons can be
spin-polarized to scatter mobile electrons, responsible for the Kondo-like
scattering observed at the LAO/STO interface.
