Magnetic polarons and the metal-semiconductor transitions in (Eu,La)B6 and EuO: Raman scattering studies

C. S. Snow, S Lance Cooper, D. P. Young, Z. Fisk, Arnaud Comment, Jean Philippe Ansermet

Research output: Contribution to journalArticle

Abstract

We present inelastic light scattering measurements of EuO and EU1-xLaxB6 (x = 0, 0.005, 0.01, 0.03, and 0.05) as functions of doping, B isotope, magnetic field, and temperature. Our results reveal a variety of distinct regimes as a function of decreasing T: (a) a paramagnetic semimetal regime, which is characterized by a collision-dominated electronic scattering response whose scattering rate Γ decreases with decreasing temperature; (b) a spin-disorder scattering regime, which is characterized by a collision-dominated electronic scattering response whose scattering rate Γ scales with the magnetic susceptibility; (c) a magnetic polaron regime, in which the development of an H = 0 spin-flip Raman response betrays the formation of magnetic polarons in a narrow temperature range above the Curie temperature Tc; and (d) a ferromagnetic metal regime, characterized by a flat electronic continuum response typical of other strongly correlated metals. By exploring the behavior of the Raman responses in these various regimes in response to changing external parameters, we are able to investigate the evolution of charge and spin degrees of freedom through various transitions in these materials.

Original languageEnglish (US)
Article number174412
Pages (from-to)1744121-17441212
Number of pages15697092
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume64
Issue number17
StatePublished - Nov 1 2001

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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