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TT: Fachverband Tiefe Temperaturen

TT 26: CE: Heavy Fermions

TT 26.13: Vortrag

Mittwoch, 24. März 2010, 17:30–17:45, H21

Enhanced thermoelectricity and strong correlations in FeSb₂ — •Niels Oeschler¹, Peijie Sun¹, Simon Johnsen², Bo B. Iversen², and Frank Steglich¹ — ¹Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ²Department of Chemistry, University of Aarhus, Aarhus, Denmark

FeSb₂ was recently identified as a narrow-gap semiconductor with indications of strong electron-electron correlations. Around 10 K the thermopower S assumes huge absolute values of more than 40 mV/K. It has been shown that the thermopower of FeSb₂ is of diffusive nature and strongly enhanced due to the appearance of strong correlations.
By substituting Te on the Sb site, an atom with one extra electron relative to Sb, an evolution from a semiconducting ground state into a metallic one is observed for small Te content. The thermopower of FeSb_1.98Te_0.02 is linear in T as expected for metals, however, with enhanced slope compared to the free-electron predictions. Deduced from specific heat and Hall effect measurements the effective charge-carrier mass m^∗ is determined to be as large as 15 times the free electron mass, consistent with the enhanced thermopower.