Retention of two-band superconductivity in highly carbon-doped MgB2

H. Schmidt; K. E. Gray; D. G. Hinks; J. F. Zasadzinski; M. Avdeev; J. D. Jorgensen; J. C. Burley

doi:10.1103/PhysRevB.68.060508

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Retention of two-band superconductivity in highly carbon-doped MgB2

H. Schmidt, K. E. Gray, D. G. Hinks, J. F. Zasadzinski, M. Avdeev, J. D. Jorgensen, J. C. Burley

DOI 10.1103/PhysRevB.68.060508 · Physical Review B

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Abstract

Tunneling data on MgB1.8C0.2 show a reduction in the energy gap of the π bands by nearly a factor of 2 from undoped MgB2 that is consistent with the Tc reduction, but inconsistent with the expectations of the dirty limit. Dirty-limit theory for undoped MgB2 predicts a single gap about three times larger than measured and a reduced Tc comparable to that measured. Our heavily doped samples exhibit a uniform dispersion of C suggestive of significantly enhanced scattering, and we conclude that the retention of two-band superconductivity in these samples is caused by a selective suppression of interband scattering.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
MgB1.8C0.2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	21.5	Pressure not reported	midpoint
MgB1.8C0.2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22.5	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	39	Pressure not reported	unknown