Optical study of archetypical valence-fluctuating Eu systems.

Physical review letters (2013-02-02)
V Guritanu, S Seiro, J Sichelschmidt, N Caroca-Canales, T Iizuka, S Kimura, C Geibel, F Steglich

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.

Product Number
Product Description

Iridium, powder, 99.9% trace metals basis
Iridium, wire, diam. 0.15 mm, 99.9% trace metals basis
Europium, ingot, under oil, 99.9% trace rare earth metals basis
Iridium, evaporation slug, diam. × L 0.6 cm × 1.2 cm, 99.9% trace metals basis
Iridium, black, powder, −200 mesh, ≥99% trace metals basis
Iridium, foil, thickness 0.25 mm, 99.9% trace metals basis