Browsing by Author "Borzenets, I"

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    Investigation of Supercurrent in the Quantum Hall Regime in Graphene Josephson Junctions
    (Journal of Low Temperature Physics, 2018-06-01) Draelos, A; Wei, MT; Seredinski, A; Ke, C; Watanabe, K; Taniguchi, T; Yamamoto, M; Tarucha, S; Borzenets, I; Amet, F; Finkelstein, G
    © 2018, Springer Science+Business Media, LLC, part of Springer Nature. In this study, we examine multiple encapsulated graphene Josephson junctions to determine which mechanisms may be responsible for the supercurrent observed in the quantum Hall (QH) regime. Rectangular junctions with various widths and lengths were studied to identify which parameters affect the occurrence of QH supercurrent. We also studied additional samples where the graphene region is extended beyond the contacts on one side, making that edge of the mesa significantly longer than the opposite edge. This is done in order to distinguish two potential mechanisms: (a) supercurrents independently flowing along both non-contacted edges of graphene mesa, and (b) opposite sides of the mesa being coupled by hybrid electron–hole modes flowing along the superconductor/graphene boundary. The supercurrent appears suppressed in extended junctions, suggesting the latter mechanism.
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    Two-stage Kondo effect and Kondo-box level spectroscopy in a carbon nanotube
    (Physical Review B - Condensed Matter and Materials Physics, 2010-10-18) Bomze, Y; Borzenets, I; Mebrahtu, H; Makarovski, A; Baranger, HU; Finkelstein, G
    The concept of the "Kondo box" describes a single spin, antiferromagnetically coupled to a quantum dot with a finite level spacing. Here, a Kondo box is formed in a carbon nanotube interacting with a localized electron. We investigate the spins of its first few eigenstates and compare them to a recent theory. In an "open" Kondo-box, strongly coupled to the leads, we observe a nonmonotonic temperature dependence of the nanotube conductance, which results from a competition between the Kondo-box singlet and the "conventional" Kondo state that couples the nanotube to the leads. © 2010 The American Physical Society.