Optical study of archetypical valence-fluctuating Eu systems.
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.
Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.
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Guritanu
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Seiro
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Sichelschmidt
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Caroca-Canales
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Iizuka
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Kimura
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Geibel
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Steglich
D004583:Electrons; D005063:Europium / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry; D055095:Optics and Photonics / Q000379:methods; D010758:Phosphorus / Q000737:chemistry; D012825:Silicon / Q000737:chemistry
D010758:Phosphorus; D007495:Iridium; D005063:Europium; D009532:Nickel; D012825:Silicon