4 research outputs found
Heat and Charge Transport Properties of MgB2
A polycrystalline sample of the MgB_2 superconductor was investigated by
measurements of the electrical resistivity, the thermopower and the thermal
conductivity in the temperature range between 1.8K and 300K in zero magnetic
field. The electrical resistivity shows a superconducting transition at
T_c=38.7K and, similarly to borocarbides, a T^2.4 behaviour up to 200K. The
electron diffusion thermopower and its bandstructure-derived value indicate the
dominant hole character of the charge carriers. The total thermopower can be
explained by the diffusion term renormalized by a significant electron-phonon
interaction and a phonon drag term. In the thermal conductivity, for decreasing
temperature, a significant decrease below T_c is observed resulting in a T^3
behaviour below 7K. The reduced Lorenz number exhibits values smaller than 1
and a characteristic minimum which resembles the behaviour of non-magnetic
borocarbides.Comment: 7 pages, 5 figures; added references and minor changes; accepted for
publication in Physica
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Intrinsische Eigenschaften ferromagnetischer Phasen : Magnetwerkstoffe ; Abschlussbericht
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