Bulletin of the American Physical Society
2018 Annual Meeting of the APS Mid-Atlantic Section
Volume 63, Number 20
Friday–Sunday, November 9–11, 2018; College Park, Maryland
Session B01: Poster Session (Day 1)
8:00 PM,
Friday, November 9, 2018
Edward St. John
Room: Lounge
Chair: Wendell T. Hill, III, University of Maryland, College Park
Abstract ID: BAPS.2018.MAS.B01.38
Abstract: B01.00038 : Probing the Superconducting Energy Gaps of an Assymetrical all-MgB2 Josephson Junction*
Presenter:
Roberto C Ramos
(University of the Sciences)
Authors:
Joseph Lambert
(University of the Sciences, National Radio Astronomy Observatory)
Masahito Sakoda
(Tokyo University of Agriculture and Technology)
Michio Naito
(Tokyo University of Agriculture and Technology)
Roberto C Ramos
(University of the Sciences)
We have previously reported high-resolution tunneling spectroscopy measurements of substructure within the two superconducting energy gaps of Magnesium diboride (MgB2) [1,2]. The samples used consisted of 1-gap/2-gap heterojunctions, where the counter-electrode is a conventional single-gap superconductor (Pb or Sn). Here, we report similar measurements of 2-gap/2-gap all-MgB2 Josephson junctions. The crystal orientations of the two MgB2 films are mostly c-axis parallel to the tunneling direction, with very small contribution from the larger σ gap. Due to differences in growth conditions, we find that the two MgB2 electrodes have different Tc's and gap values. We analyze our dI/dV measurements using a modified tunneling model where each electrode is represented as a weighted sum of two BCS densities of states. We observe (1) a transition from SIS to NIS behavior as temperature increases past the lower Tc electrode, and (2) the presence of multiple quasiparticle peaks due to the sums and differences in pairwise combinations of disparate π and σ gap values within each electrode.
[1] S. Carabello, et. al., Supercond. Sci. Technol. 28, 055015 (2015).
[2] K. Chen, et. al., Nat. Comm., 3, 619, (2012).
*R.C.Ramos acknowledges support from the National Science Foundation DMR 1555775
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.MAS.B01.38
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