Optical study of archetypical valence-fluctuating Eu systems

Phys Rev Lett. 2012 Dec 14;109(24):247207. doi: 10.1103/PhysRevLett.109.247207. Epub 2012 Dec 12.

Abstract

We have investigated the optical conductivity of the prominent valence-fluctuating compounds EuIr(2)Si(2) and EuNi(2)P(2) in the infrared energy range to get new insights into the electronic properties of valence-fluctuating systems. For both compounds, we observe upon cooling the formation of a renormalized Drude response, a partial suppression of the optical conductivity below 100 meV, and the appearance of a midinfrared peak at 0.15 eV for EuIr(2)Si(2) and 0.13 eV for EuNi(2)P(2). Most remarkably, our results show a strong similarity with the optical spectra reported for many Ce- or Yb-based heavy-fermion metals and intermediate valence systems, although the phase diagrams and the temperature dependence of the valence differ strongly between Eu systems and Ce- or Yb-based systems. This suggests that the hybridization between 4f and conduction electrons, which is responsible for the properties of Ce and Yb systems, plays an important role in valence-fluctuating Eu systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electrons
  • Europium / chemistry*
  • Iridium / chemistry
  • Models, Chemical*
  • Nickel / chemistry
  • Optics and Photonics / methods
  • Phosphorus / chemistry
  • Silicon / chemistry

Substances

  • Phosphorus
  • Iridium
  • Europium
  • Nickel
  • Silicon