Optical properties and electronic structure of the nonmetallic metal FeCrAs

A. Akrap, Y. M. Dai, Wen-Chin Wu, S. R. Julian, C. C. Homes

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The complex optical properties of a single crystal of hexagonal FeCrAs (TNâ‰125 K) have been determined above and below TN over a wide frequency range in the planes (along the b axis) and along the perpendicular (c-axis) direction. At room temperature, the optical conductivity σ1(ω) has an anisotropic metallic character. The electronic band structure reveals two bands crossing the Fermi level, allowing the optical properties to be described by two free-carrier (Drude) contributions consisting of a strong, broad component and a weak, narrow term that describes the increase in σ1(ω) below â‰15 meV. The dc resistivity of FeCrAs is "nonmetallic," meaning that it rises in power-law fashion with decreasing temperature, without any signature of a transport gap. In the analysis of the optical conductivity, the scattering rates for both Drude contributions track the dc resistivity quite well, leading us to conclude that the nonmetallic resistivity of FeCrAs is primarily due to a scattering rate that increases with decreasing temperature, rather than the loss of free carriers. The power law σ1(ω) ω-0.6 is observed in the near-infrared region and as T→TN spectral weight is transferred from low to high energy (â‰0.6 eV); these effects may be explained by either the two-Drude model or Hund's coupling. We also find that a low-frequency in-plane phonon mode decreases in frequency for T<TN, suggesting the possibility of spin-phonon coupling.

Original languageEnglish
Article number125115
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume89
Issue number12
DOIs
Publication statusPublished - 2014 Mar 17

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Optical conductivity
Electronic structure
Optical properties
Metals
electronic structure
optical properties
electrical resistivity
Scattering
metals
conductivity
Fermi level
scattering
Band structure
Temperature
frequency ranges
signatures
Single crystals
low frequencies
Infrared radiation
temperature

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Optical properties and electronic structure of the nonmetallic metal FeCrAs. / Akrap, A.; Dai, Y. M.; Wu, Wen-Chin; Julian, S. R.; Homes, C. C.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 89, No. 12, 125115, 17.03.2014.

Research output: Contribution to journalArticle

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