title: "Giant" enhancement of the upper critical field and fluctuations above the bulk Tc in superconducting ultrathin lead nanowire arrays.
abstract: We have produced ultrathin lead (Pb) nanowires in the 6 nm pores of SBA-15 mesoporous silica substrates by chemical vapor deposition. The nanowires form regular and dense arrays. We demonstrate that bulk Pb (a type-I superconductor below Tc = 7.2 K with a critical field of 800 Oe) can be tailored by nanostructuring to become a type-II superconductor with an upper critical field (Hc2) exceeding 15 T and signs of Cooper pairing 3-4 K above the bulk Tc. The material undergoes a crossover from a one-dimensional fluctuating superconducting state at high temperatures to three-dimensional long-range-ordered superconductivity in the low-temperature regime. We show with our data in an impressive way that superconductivity in elemental metals can be greatly enhanced by nanostructuring.
authors.affiliation: Department of Physics and the William Mong Institute of Nano Science and Technology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Mingquan
authors.initials: M
authors.lastname: He
authors.forename: Chi Ho
authors.initials: CH
authors.lastname: Wong
authors.forename: Pok Lam
authors.initials: PL
authors.lastname: Tse
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Haijing
authors.initials: H
authors.lastname: Zhang
authors.forename: Frank L Y
authors.initials: FL
authors.lastname: Lam
authors.forename: Ping
authors.initials: P
authors.lastname: Sheng
authors.forename: Xijun
authors.initials: X
authors.lastname: Hu
authors.forename: Rolf
authors.initials: R
authors.lastname: Lortz
mesh_terms: D004553:Electric Conductivity; D007854:Lead / Q000737:chemistry*; D060328:Magnetic Phenomena; D036103:Nanotechnology / Q000295:instrumentation*; D053770:Nanowires; D013696:Temperature
chemical_list: D007854:Lead