Quantum Size Effects on the Perpendicular Upper Critical Field in Ultrathin Lead Films

Department of Physics, Oklahoma State University - Stillwater, SWO, Oklahoma, United States
Physical Review Letters (Impact Factor: 7.51). 01/2006; 95(24):247005. DOI: 10.1103/PhysRevLett.95.247005
Source: PubMed


We report the thickness-dependent (in terms of atomic layers) oscillation behavior of the perpendicular upper critical field Hc2perpendicular in the ultrathin lead films at the reduced temperature (t = T/Tc). Distinct oscillations of the normal-state resistivity as a function of film thickness have also been observed. Compared with the Tc oscillation, the Hc2perpendicular shows a considerable large oscillation amplitude and a pi phase shift. The oscillatory mean free path caused by the quantum size effect plays a role in Hc2perpendicular oscillation.


Available from: Yupeng Wang
  • Source
    • "Superconductivity in thin metallic films with a thickness at atomic limit has been shown to persist to thicknesses much below the superconducting coherence length and even down to a single layer films [26] [27] [28] [29] [30] [31] [32]. Interestingly, in low dimensional superconductors, the superconducting coherence length (ξ) or the magnetic penetration depth (λ) do not define the critical length scale for the destruction of the superconducting state. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In multiband superconductivity, the case where the single electron hopping between different Fermi surface spots of different symmetry is forbidden by selection rules is recently attracting a large interest. The focus is addressed to superconductivity made of multiple condensates with different symmetry where the chemical potential crosses a 2.5 Lifshitz transition. This can now be investigated experimentally by fine-tuning of the chemical potential in the range of tens meV around a band edge using gate voltage control. We discuss here the case of the two-dimensional electron gas (2DEG), at the interface between two insulating oxides confined within a slab of 5 nanometers thickness, where the electronic structure is made of subbands generated by quantum size effects. We focus on the case of the BCS-BEC transition in the upper subband for different pairing strength in the shallow Fermi surface.
    Journal of Physics Conference Series 12/2013; 529(1). DOI:10.1088/1742-6596/529/1/012007
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pb nanobridges with a thickness of less than 10 nm and a width of several hundred nm have been fabricated from single-crystalline Pb films using low-temperature molecular beam epitaxy and focus ion beam microfabrication techniques. We observed novel magnetoresistance oscillations below the superconducting transition temperature (T C ) of the bridges. The oscillations—which were not seen in the crystalline Pb films—may originate from the inhomogeneity of superconductivity induced by the applied magnetic fields on approaching the normal state, or the degradation of film quality by thermal evolution.
    Nano Research 09/2009; 2(9):671-677. DOI:10.1007/s12274-009-9070-3 · 7.01 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper summarizes our recent work on the study of quantum size effects (QSE) and novel physical properties of the Pb/Si (111) heterostructure. Two different types of samples were investigated. One is wedge-shaped Pb islands, and the other is atomically flat Pb thin films. With scanning tunneling microscopy (STM) manipulation, we observed an intriguing morphology dynamics of the islands that swings between two extreme energy states, like that in a classical pendulum. We show that the dynamics is a result of the competition between the QSE and the classical step free energy minimizing effect. For the second type of the samples, the QSE is studied in terms of thickness-dependent film stability, electronic structure and physical properties by using STM, angle-resolved photoemission spectroscopy (ARPES) and transport measurement. The results consistently reveal the formation of quantum well states (QWS) due to electron confinement in the films. This size effect could greatly modify the electronic structure near the Fermi level and lead to quantum oscillations in superconductivity, electron-phonon coupling and thermal expansion. The work unambiguously demonstrates the possibility of quantum engineering of physical properties of thin films by exploiting well-controlled and thickness-dependent QSE.
    Frontiers of Physics in China 01/2006; 1(3):323-333. DOI:10.1007/s11467-006-0021-0 · 1.44 Impact Factor
Show more