Effect of the four-sheet Fermi surface on magnetoresistivity of MgB2 |
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Authors: | I Pallecchi M Monni C Ferdeghini V Ferrando M Putti C Tarantini E Galleani D'Agliano |
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Institution: | (1) LAMIA-CNR- INFM and Università di Genova, via Dodecaneso 33, 16146 Genova, Italy;(2) CNISM, Unità di Genova, via Dodecaneso 33, 16146 Genova, Italy |
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Abstract: | Recent experimental data of anisotropic magnetoresistivity measured in
MgB2 films have shown an intriguing behaviour: the angular dependence
of magnetoresistivity changes dramatically with temperature and disorder. In
order to explain such phenomenology, in this work, we extend our previous
analyses on multiband transverse magnetoresistivity in magnesium diboride,
by calculating its analytic expression, assuming a constant anisotropic
Fermi surface mass tensor. The calculation is done for arbitrary
orientation of the magnetic field with respect to the crystalline axes and
for the current density either perpendicular or parallel to the magnetic
field. This approach allows to extract quite univocally the values of the
scattering times in the σ- and π-bands by fitting experimental data with a
simple analytic expression.
We also extend the analysis to the magnetoresistivity of polycrystalline
samples, with an arbitrary angle between the current density and the
magnetic field, taking into account the anisotropy of each randomly oriented
grain.
Thereby, we propose magnetoresistivity as a very powerful characterization
tool to explore the effect of disorder by irradiation or selective doping as
well as of phonon scattering in each one of the two types of bands, in
single crystals and polycrystalline samples, which is a crucial issue in the
study of magnesium diboride. |
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Keywords: | 74 70 Ad Metals alloys and binary compounds (including A15 MgB2 etc ) 75 47 Np Metals and alloys |
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