title: Evidence for bulk superconductivity in pure bismuth single crystals at ambient pressure.
abstract: At ambient pressure, bulk rhombohedral bismuth is a semimetal that remains in the normal state down to at least 10 millikelvin. Superconductivity in bulk bismuth is thought to be unlikely because of the extremely low carrier density. We observed bulk superconductivity in pure bismuth single crystals below 0.53 millikelvin at ambient pressure, with an estimated critical magnetic field of 5.2 microteslas at 0 kelvin. Superconductivity in bismuth cannot be explained by the conventional Bardeen-Cooper-Schrieffer theory because its adiabatic approximation does not hold true for bismuth. Future theoretical work will be needed to understand superconductivity in the nonadiabatic limit in systems with low carrier densities and unusual band structures, such as bismuth.
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India.
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India.
authors.forename: Anil
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India.
authors.forename: A
authors.initials: A
authors.lastname: Thamizhavel
authors.affiliation: Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India. ramky@tifr.res.in.
authors.forename: S
authors.initials: S
authors.lastname: Ramakrishnan