title: Superconductivity modulated by quantum size effects.
abstract: We have fabricated ultrathin lead films on silicon substrates with atomic-scale control of the thickness over a macroscopic area. We observed oscillatory behavior of the superconducting transition temperature when the film thickness was increased by one atomic layer at a time. This oscillating behavior was shown to be a manifestation of the Fabry-Perot interference modes of electron de Broglie waves (quantum well states) in the films, which modulate the electron density of states near the Fermi level and the electron-phonon coupling, which are the two factors that control superconductivity transitions. This result suggests the possibility of modifying superconductivity and other physical properties of a thin film by exploiting well-controlled and thickness-dependent quantum size effects.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Guo
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Zhang
authors.forename: Xin-Yu
authors.initials: XY
authors.lastname: Bao
authors.forename: Tie-Zhu
authors.initials: TZ
authors.lastname: Han
authors.forename: Zhe
authors.initials: Z
authors.lastname: Tang
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Zhang
authors.forename: Wen-Guang
authors.initials: WG
authors.lastname: Zhu
authors.forename: E G
authors.initials: EG
authors.lastname: Wang
authors.forename: Qian
authors.initials: Q
authors.lastname: Niu
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Qiu
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Jia
authors.forename: Zhong-Xian
authors.initials: ZX
authors.lastname: Zhao
authors.forename: Qi-Kun
authors.initials: QK
authors.lastname: Xue