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Abstract:
We show that the colossal thermoelectric power S(T) observed in the
correlated semiconductor FeSb2 below 30 K is accompanied by a huge
Nernst coefficient nu(T) and magnetoresistance MR(T). Markedly, the
latter two quantities are enhanced in a strikingly similar manner. While
in the same temperature range, S(T) of the reference compound FeAs2,
which has a seven-times-larger energy gap, amounts to nearly half of
that of FeSb2, its nu(T) andMR(T) are intrinsically different to FeSb2:
They are smaller by two orders of magnitude and have no common features.
Underlying the essentially different thermoelectric properties between
FeSb2 and FeAs2, a large mismatch between the electrical and thermal
Hall mobilities is found only in the former compound. With the charge
transport of FeAs2 successfully captured by the density functional
theory, we emphasize a significantly dispersive electron-relaxation time
tau(epsilon(k)) related to electron-electron correlations to be at the
heart of the peculiar thermoelectricity and magnetoresistance of FeSb2.
