Effect of Magnetic Impurities in a Two-Band Superconductor: A Point-Contact Study of Mn-Substituted MgB2 Single Crystals
R. S. Gonnelli, D. Daghero, G. A. Ummarino, A. Calzolari, M. Tortello, V. A. Stepanov, N. D. Zhigadlo, K. Rogacki, J. Karpinski, F. Bernardini, S. Massidda
DOI 10.1103/PhysRevLett.97.037001 · Physical Review Letters
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Abstract
We present the first results of directional point-contact measurements in Mg1−xMnxB2 single crystals, with x up to 0.015 and bulk Tc down to 13.3 K. The order parameters Δσ and Δπ were obtained by fitting the conductance curves with the two-band Blonder-Tinkham-Klapwijk model. Both Δπ and Δσ decrease with the critical temperature of the junctions TcA, but remain clearly distinct up to the highest Mn content. Once analyzed within the Eliashberg theory, the results indicate that spin-flip scattering is dominant in the σ band, as also confirmed by first-principles band-structure calculations.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Mg1-xMnxB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 33.9 | Pressure not reported | unknown |
| Mg1-xMnxB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 13.3 | Pressure not reported | unknown |
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 39.4 | Pressure not reported | unknown |
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