Pudding-mold-type band as an origin of the large seebeck coefficient coexisting with metallic conductivity in carrier-doped FeAs2 and PtSe2

Hidetomo Usui, Kazuhiko Kuroki, Seiya Nakano, Kazutaka Kudo, Minoru Nohara

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

We theoretically study the thermoelectric properties of electron-doped FeAs2 and hole-doped PtSe2 from a band-structure point of view using first-principles band calculations. The band structure of both materials has a peculiar band shape with a flat portion at the top (bottom) of the band, namely the pudding-mold-type band as found in Na x CoO 2. The pudding-mold-type band has a quasi-one-dimensional nature in FeAs2 and a quasi-two-dimensional nature in PtSe2. We study the origins of the pudding-mold-type band and find that the dz2 orbital in FeAs2, and not only the p z but also the p x and the p y orbitals in PtSe2 play an important role in making the pudding-mold-type band. We calculate the Seebeck coefficients by the Boltzmann equation approach using a tight-binding model constructed from first-principles band calculations, finding values close to experimental observations. The present study shows the general efficiency of the pudding-mold-type band. We suggest that an efficient route towards obtaining good thermoelectric materials is to realize ideal pudding-mold-type bands by modification of lattice structures.

Original languageEnglish
Pages (from-to)1656-1661
Number of pages6
JournalJournal of Electronic Materials
Volume43
Issue number6
DOIs
Publication statusPublished - 2014

Keywords

  • Thermoelectric effect
  • band structure
  • first-principles calculation
  • structure dependence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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