Thermoelectricity and electronic properties of Y1xCexCrB4

Sever Flipo, Helge Rosner, Matej Bobnar, Kristina O. Kvashnina, Andreas Leithe-Jasper, and Roman Gumeniuk
Phys. Rev. B 103, 195121 – Published 11 May 2021
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Abstract

Boron-rich materials combine chemical stability with refractory properties and, consequently, are interesting for high-temperature thermoelectric applications. Therefore, the magnetic, electrical, and thermal transport properties of the Y1xCexCrB4 series have been investigated here to employ the concept of correlation-enhanced thermoelectric properties. Combining x-ray diffraction and energy- or wavelength-dispersive spectrometry, we find a rather narrow stability range of Y1xCexCrB4, only samples on the Y- and Ce-rich substitution limits (x=0,0.05,0.95,and1) were obtained. Electrical resistivity data show a change from semiconducting (x=0) to metallic behavior upon Ce substitution (x0.95). From magnetic susceptibility measurements and x-ray absorption spectroscopy, we find a temperature-dependent intermediate valence state of Ce of about +3.5. However, a fit of the magnetic susceptibility data to the Coqblin-Schrieffer model yields a surprisingly high Kondo temperature of about 1100 K. Together with the good thermal conductivity for the studied substitution series this impedes a suitable thermoelectric performance. Electronic structure calculations for YCrB4 support its narrow gap semiconducting nature in contrast to previous studies. Surprisingly, its electronic structure is characterized by pronounced van Hove singularities very close to the Fermi-level EF. They originate from nearly dispersionless Cr 3dz2r2-derived bands in a large part of the Brillouin zone, suggesting the appearance of electronic instabilities upon rather small electron doping into these states.

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  • Received 27 October 2020
  • Revised 24 March 2021
  • Accepted 16 April 2021

DOI:https://doi.org/10.1103/PhysRevB.103.195121

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Sever Flipo1,2, Helge Rosner2, Matej Bobnar2, Kristina O. Kvashnina3,4, Andreas Leithe-Jasper2, and Roman Gumeniuk1,*

  • 1Institut für Experimentelle Physik, TU Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg, Germany
  • 2Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden, Germany
  • 3Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstrasse 400, 01328 Dresden, Germany
  • 4The Rossendorf Beamline at ESRF, CS 40220, 38043 Grenoble Cedex 9, France

  • *roman.gumeniuk@physik.tu-freiberg.de

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Issue

Vol. 103, Iss. 19 — 15 May 2021

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