Resonant Charge Relaxation as a Likely Source of the Enhanced Thermopower in FeSi

Abstract

The enhanced thermopower of the correlated semiconductor FeSi is found to be robust against the sign of the relevant charge carriers. At $T$\,$\approx$\,70 K, the position of both the high-temperature shoulder of the thermopower peak and the nonmagnetic-enhanced paramagnetic crossover, the Nernst coefficient $\nu$ assumes a large maximum and the Hall mobility ${\mu }_H$ diminishes to below 1 cm${}^2$/Vs. These cause the dimension-less ratio $\nu$/${\mu }_H$ $-$ a measure of the energy dispersion of the charge scattering time $\tau (\epsilon )$ $-$ to exceed that of classical metals and semiconductors by two orders of magnitude. Concomitantly, the resistivity exhibits a hump and the magnetoresistance changes its sign. Our observations hint at a resonant scattering of the charge carriers at the magnetic crossover, imposing strong constraints on the microscopic interpretation of the robust thermopower enhancement in FeSi.

arXiv comment5 pages, 3 figures

References in corpus (12)

• The onset of the vortex-like Nernst signal above Tc in La_{2-x}Sr_xCuO_4 and Bi_2Sr_{2-y}La_yCuO_6
• Mott Relation for Anomalous Hall and Nernst effects in Ga1-xMnxAs Ferromagnetic Semiconductors
• Large Anomalous Hall effect in a silicon-based magnetic semiconductor
• Magnetoresistance From Quantum Interference Effects in Ferromagnets
• The Nernst effect and the boundaries of the Fermi liquid picture
• Signatures of electronic correlations in iron silicide
• Theory of the thermoelectricity of intermetallic compounds with Ce or Yb ions
• Thermoelectric properties of Co, Ir, and Os-Doped FeSi Alloys: Evidence for Strong Electron-Phonon Coupling
• Temperature dependent correlations in covalent insulators
• Nernst Effect as a Probe of Local Kondo Scattering in Heavy Fermions
• Highly Dispersive Electron Relaxation and Colossal Thermoelectricity in the Correlated Semiconductor FeSb${}_2$
• Thermoelectric response in the incoherent transport region near Mott transition: the case study of La1-xSrxVO3

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• Extraordinary Bulk Insulating Behavior in the Strongly Correlated Materials FeSi and FeSb${}_2$