Controlling Kondo-like Scattering at the SrTiO3-based Interfaces

TL;DR

This study investigates how lattice mismatch and oxygen pressure influence Kondo-like scattering at SrTiO3-based interfaces, revealing that increased mismatch and oxygen pressure enhance localized Ti3+ ions, leading to magnetic scattering effects.

Contribution

It demonstrates the control of Kondo-like scattering through lattice mismatch and oxygen pressure, highlighting the role of localized Ti3+ ions at oxide interfaces.

Findings

Larger lattice mismatch increases Kondo-like scattering.

Higher oxygen pressure enhances localized Ti3+ ions.

Localized Ti3+ ions cause magnetic scattering at interfaces.

Abstract

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.