控制基于 SrTiO3 的界面中的类 Kondo 散射。

Controlling Kondo-like Scattering at the SrTiO3-based Interfaces.

机构信息

NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.

Department of Physics, National University of Singapore, Singapore 117542, Singapore.

出版信息

Sci Rep. 2016 May 5;6:25455. doi: 10.1038/srep25455.

DOI:10.1038/srep25455

PMID:27147407

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4857089/

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 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.

摘要

近年来，人们对非磁性氧化物界面处的磁相互作用观察产生了浓厚的兴趣。在本报告中，我们表明，通过增加晶格失配度和生长氧压 $PO_2$，可以增强基于 SrTiO3 的导电界面处的类 Kondo 散射。对于晶格失配度为 3.0%的 26 个晶胞的 LaAlO3/SrTiO3（LAO/STO）界面，当 $PO_2$ 超过 1 mTorr 时，观察到类 Kondo 散射。相比之下，当晶格失配度降低到（La0.3Sr0.7）（Al0.65Ta0.35）O3/SrTiO3（LSAT/STO）界面的 1.0%时，在 100 mTorr 的 $PO_2$ 下，金属态始终得以保持。霍尔测量和 X 射线吸收近边结构（XANES）光谱的数据表明，与 LSAT/STO 相比，LAO/STO 界面处形成了更多的局域 Ti(3+) 离子。这些具有未配对电子的局域 Ti(3+) 离子可以被自旋极化，散射移动电子，这是在 LAO/STO 界面处观察到的类 Kondo 散射的原因。