Temperature dependence of the Mott gap in single-layer 1T-TaSe<sub>2</sub> revealed by scanning tunneling spectroscopy

ORAL

Abstract

A key to unraveling the high-temperature superconductivity mechanism in cuprates is to understand the Metal-insulator transition in Mott insulators that can be induced by either doping charge or raising temperature. While the doping dependence of the Mott gap in cuprates has been studied extensively, it is difficult to explore the gap's temperature dependence in these systems due to its large size (typically 1~2 eV) and the resulting high temperature scale required to melt the Mott-state. Here we use scanning tunneling microscopy/spectroscopy to investigate the temperature dependence of the electronic structure of the single-layer Mott insulator 1T-TaSe2 which has a much more modest Mott gap of ~ 0.1 eV. We observe that the gap closes rapidly at a temperature scale that is significantly smaller than the gap size. This is accompanied by changes in the exotic orbital texture of the upper Hubbard band that are consistent with reduced screening at elevated temperatures. This phenomenon is unique among strongly correlated systems and is compatible with recent theoretical predictions where spin fluctuations are responsible for the rapid gap closing.

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Presenters

  • Wei Ruan

    • University of California, Berkeley

Authors

  • Wei Ruan

    • University of California, Berkeley

  • Yi Chen

    • University of California, Berkeley

  • Jinwoong Hwang

    • Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Lab
    • Physics, Pusan National University

  • Shujie Tang

    • Standford
    • Stanford University
    • Stanford Univeristy
    • Geballe Laboratory for Advanced Materials, Stanford University

  • Ryan Lee

    • University of California, Berkeley

  • Hsin-Zon Tsai

    • University of California, Berkeley

  • Salman Abdul Gaffar Kahn

    • University of California, Berkeley

  • Franklin Liou

    • University of California, Berkeley

  • Andrew Aikawa

    • University of California, Berkeley

  • Zhixun Shen

    • Standford
    • Stanford University
    • Stanford Univeristy
    • Applied Physics, Stanford University
    • SLAC National Accelerator Laboratory
    • Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University
    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
    • Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory
    • SIMES, SLAC - Natl Accelerator Lab
    • Stanford Univ

  • Sung-Kwan Mo

    • Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Lab
    • Advanced Light Source, Lawrence Berkeley National Lab
    • Advanced Light Source, Lawrence Berkeley National Laboratory
    • ALS, Lawrence Berkeley National Laboratory

  • Michael F Crommie

    • Lawrence Berkeley National Lab and UC Berkeley
    • University of California, Berkeley