title: Effect of magnetic impurities in a two-band superconductor: a point-contact study of mn-substituted single crystals.
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 Deltasigma and Deltapi were obtained by fitting the conductance curves with the two-band Blonder-Tinkham-Klapwijk model. BothDeltapi and Deltasigma decrease with the critical temperature of the junctions TAC, 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 sigma band, as also confirmed by first-principles band-structure calculations.
authors.affiliation: Dipartimento di Fisica and CNISM, Politecnico di Torino, 10129 Torino, Italy.
authors.forename: R S
authors.initials: RS
authors.lastname: Gonnelli
authors.forename: D
authors.initials: D
authors.lastname: Daghero
authors.forename: G A
authors.initials: GA
authors.lastname: Ummarino
authors.forename: A
authors.initials: A
authors.lastname: Calzolari
authors.forename: M
authors.initials: M
authors.lastname: Tortello
authors.forename: V A
authors.initials: VA
authors.lastname: Stepanov
authors.forename: N D
authors.initials: ND
authors.lastname: Zhigadlo
authors.forename: K
authors.initials: K
authors.lastname: Rogacki
authors.forename: J
authors.initials: J
authors.lastname: Karpinski
authors.forename: F
authors.initials: F
authors.lastname: Bernardini
authors.forename: S
authors.initials: S
authors.lastname: Massidda