We present the results of directional point-contact measurements in MgB2 single crystals, in magnetic fields up to 9 T parallel to the c axis. By fitting the conductance curves of our point contacts—showing clear Andreev-reflection features—with a generalized Blonder-Tinkham-Klapwijk model, we extracted the values of the two gaps Ds and Dp . The resulting Ds(B) and Dp(B) curves agree very well with the predictions of the two-band model in dirty limit when the p-band diffusivity is a few times greater than the s-band one. This result concurs with other experimental and theoretical findings in indicating that, even in the best crystals, the p band is moderately dirty.

Magnetic-field dependence of the gaps in a two-band superconductor: a point-contact study of MgB2 single crystals / Gonnelli, Renato; Daghero, Dario; Calzolari, Andrea; Ummarino, Giovanni; Dellarocca, Valeria; Stepanov, V. A.; Jun, J.; Kazakov, S. M.; Karpinski, J.. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 69:(2004), pp. 100504-1-100504-4. [10.1103/PhysRevB.69.100504]

Magnetic-field dependence of the gaps in a two-band superconductor: a point-contact study of MgB2 single crystals

GONNELLI, Renato;DAGHERO, Dario;CALZOLARI, ANDREA;UMMARINO, Giovanni;DELLAROCCA, Valeria;
2004

Abstract

We present the results of directional point-contact measurements in MgB2 single crystals, in magnetic fields up to 9 T parallel to the c axis. By fitting the conductance curves of our point contacts—showing clear Andreev-reflection features—with a generalized Blonder-Tinkham-Klapwijk model, we extracted the values of the two gaps Ds and Dp . The resulting Ds(B) and Dp(B) curves agree very well with the predictions of the two-band model in dirty limit when the p-band diffusivity is a few times greater than the s-band one. This result concurs with other experimental and theoretical findings in indicating that, even in the best crystals, the p band is moderately dirty.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/1402404
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