title: Size-dependent superconducting state of individual nanosized Pb islands grown on Si(111) by tunneling spectroscopy.
abstract: By measuring the temperature-dependent tunneling spectroscopy of a set of flat-top Pb islands from 3.2 to 15 K, the limiting size of a nine-monolayer-thick Pb island with superconductivity above 3.2 K was determined to be ∼ 30 nm(2), in good agreement with the Anderson criterion. Further analysis indicates that the zero-temperature energy gap decreases significantly faster than the transition temperature when the Pb island size approaches this limit. This leads to a decrease of 2Δ(0)/k(B)T(C) from 4.5 to 3.3, thus showing that the Pb island superconductors undergo a change from strong to weak electron-phonon coupling.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, People's Republic of China.
authors.forename: Jiepeng
authors.initials: J
authors.lastname: Liu
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Wu
authors.forename: Fangfei
authors.initials: F
authors.lastname: Ming
authors.forename: Xieqiu
authors.initials: X
authors.lastname: Zhang
authors.forename: Kedong
authors.initials: K
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.forename: Xudong
authors.initials: X
authors.lastname: Xiao