Spectroscopy of the rare-earth hexaborides: From correlation gaps to colossal magnetoresistance

S. L. Cooper, P. Nyhus, S. Yoon, Z. Fisk, J. Sarrao

Research output: Contribution to journalArticlepeer-review


We present a temperature- and field-dependent Raman scattering study of the "metal-semiconductor" transitions in SmB6 and EuB6. Below a characteristic temperature T* ∼ 50 K, the Raman scattering spectrum of SmB6 is characterized by (i) an abrupt redistribution of electronic scattering intensity across a temperature-independent energy, Δc, reflecting the opening of a pseudo-gap, and (ii) the appearance of several in-gap resonances which appear to be crystal-electric-field transitions of the Sm3 + ion which are split by local lattice distortions. By contrast, the metal-semiconductor (MS) transition in EuB6 manifests itself as a change from a diffusive electronic scattering response in the high-temperature paramagnetic phase, to a flat continuum scattering response in the low-temperature ferromagnetic metal phase which is characteristic of a strongly-correlated metal. Most interesting is evidence that the MS transition in EuB6 is precipitated by the formation of bound magnetic polarons.

Original languageEnglish (US)
Pages (from-to)133-137
Number of pages5
JournalPhysica B: Condensed Matter
StatePublished - Jan 1 1998


  • Colossal magnetoresistance
  • EuB
  • Kondo insulator
  • Raman spectroscopy
  • Rare-earth hexacarbides
  • SmB

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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