Magneto-thermopower of single-crystal MgB2: Evidence for strong electron-phonon coupling anisotropyстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.
Аннотация:The thermoelectric power of superconducting MgB2 single crystals was measured in the temperature range 4-300 K and in a magnetic field up to 13 T. Both the in-plane (S-ab) and out-of-plane (S-c) thermopowers was found to be positive, with similar, metal-like temperature dependences and an anisotropy ratio S-ab/S-c of the order of 3-4 in the whole temperature range. Unexpectedly low values of S-c were qualitatively explained by the properties of the Fermi surface topology. The analysis of the low temperature (T<40 K), normal-state thermopower measured in the magnetic field indicated a domination of the phonon-drag thermopower over the diffusive contribution and gave evidence of a strong (by a factor of 7+/-1) anisotropy of the electron-phonon coupling. The positive magnetothermopower found above T-c for both directions as well as a negative feature in S-c(T) at Tsimilar to27 K for B>2T were tentatively attributed to phonon-drag effects.