Tuning the Kondo effect via gating-controlled orbital selection in the LaAlO3/SrTiO3 interfacial d-electron system

Yuedong Yan, Linhai Guo, Lin Li, Laiming Wei, Weiqiang Chen, Changgan Zeng, and Jianguo Hou
Phys. Rev. B 101, 035119 – Published 13 January 2020
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Abstract

The orbital degree of freedom plays a critical role in contemporary condensed-matter physics, with recent discoveries of orbital-dependent many-body effects including electron correlation and superconductivity. Nevertheless, these orbital-dependent many-body effects have mainly been observed in bulk materials, wherein the electrons' orbital attribute is challenging to tailor selectively. Here, by planar tunneling into the two-dimensional electron system (2DES) at the LaAlO3/SrTiO3 interface, we observed a Kondo resonance, a model many-body phenomenon. The observation of the Kondo resonance provides an ideal opportunity to quantitatively exploit the emerging interfacial Kondo physics. Furthermore, it was found that the Kondo coupling strength and resonance line shape can be effectively regulated by electrostatic gating and show a sharp transition at the Lifshitz point, where the orbital occupancy of the 2DES changes from only dxy to both dxy and dxz/yz. This unusual behavior is attributed to the orbital selectivity effect in this unique multiple-d-band system, wherein the itinerant dxy and dxz/yz electrons have different orbital symmetries and therefore different Kondo exchange coupling with the localized dxy electrons. The present study may pave the way for manipulating many-body effects in 2D multiband materials via orbital engineering of itinerant electrons.

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  • Received 19 June 2019
  • Revised 6 November 2019

DOI:https://doi.org/10.1103/PhysRevB.101.035119

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Yuedong Yan1,2, Linhai Guo1,2, Lin Li3, Laiming Wei1,2, Weiqiang Chen4, Changgan Zeng1,2,*, and Jianguo Hou1

  • 1International Center for Quantum Design of Functional Materials, Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
  • 2CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
  • 3College of Physics and Electronic Engineering and Center for Computational Sciences, Sichuan Normal University, Chengdu, Sichuan 610068, China
  • 4Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology of China, Shenzhen, Guangdong 518055, China

  • *Corresponding author: cgzeng@ustc.edu.cn

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Issue

Vol. 101, Iss. 3 — 15 January 2020

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