Magnetic-field dependence of the gaps in a two-band superconductor: A point-contact study of MgB2 single crystals
R. S. Gonnelli, D. Daghero, A. Calzolari, G. A. Ummarino, Valeria Dellarocca, V. A. Stepanov, J. Jun, S. M. Kazakov, J. Karpinski
DOI 10.1103/PhysRevB.69.100504 · Physical Review B
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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 Δσ and Δπ. The resulting Δσ(B) and Δπ(B) curves agree very well with the predictions of the two-band model in dirty limit when the π-band diffusivity is a few times greater than the σ-band one. This result concurs with other experimental and theoretical findings in indicating that, even in the best crystals, the π band is moderately dirty.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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