Camelback-shaped band reconciles heavy-electron behavior with weak electronic Coulomb correlations in superconducting TlNi$_{2}$Se$_{2}$

ORAL

Abstract

Combining photoemission spectroscopy, Raman spectroscopy, and first-principles calculations, we characterize superconducting TlNi$_{2}$Se$_{2}$ as a material with weak electronic Coulomb correlations leading to a bandwidth renormalization of 1.4. We identify a camelback-shaped band, whose energetic position strongly depends on the selenium height. While this feature is universal in transition metal pnictides, in TlNi$_2$Se$_2$ it lies in the immediate vicinity of the Fermi level, giving rise to a pronounced van Hove singularity (VHS). The resulting heavy band mass resolves the apparent puzzle of a large normal-state Sommerfeld coefficient in this weakly correlated compound. The correlation effect evolution in pnictides upon d-shell filling in the presence of significant Hund's exchange coupling will also be discussed.

–

Authors

  • Christian Matt

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland

  • Nan Xu

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland

  • A. van Roekeghem

    • Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France

  • S. Biermann

    • Ecole Polytechnique, CNRS-UMR7644, 91128 Palaiseau, France

  • P. Richard

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • X. Shi

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • S.-F. Wu

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • H. W. Liu

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • D. Chen

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • T. Qian

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • H. Ding

    • Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

  • H. Wang

    • Department of Physics, Zhejiang University, Hangzhou 310027, China

  • Q. Mao

    • Department of Physics, Zhejiang University, Hangzhou 310027, China

  • J. Du

    • Department of Physics, Zhejiang University, Hangzhou 310027, China

  • M. Fang

    • Department of Physics, Zhejiang University, Hangzhou 310027, China

  • N. Plumb

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland

  • M. Radovic

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland

  • J. Mesot

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland

  • M. Shi

    • Swiss Light Source, Paul Scherrer Insitut, CH-5232 Villigen PSI, Switzerland