Josephson effect for SU(4) carbon-nanotube quantum dots

A. Zazunov, A. Levy Yeyati, and R. Egger
Phys. Rev. B 81, 012502 – Published 8 January 2010

Abstract

We present the theory of the Josephson effect in nanotube dots where an SU(4) symmetry can be realized. We find a remarkably rich phase diagram that significantly differs from the SU(2) case. In particular, π-junction behavior is largely suppressed. We analytically obtain the Josephson current in various parameter regions: (i) in the Kondo regime covering the full crossover from SU(4) to SU(2), (ii) for weak tunnel couplings, and (iii) for a large BCS gap. The transition between these regions is studied numerically.

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  • Received 24 November 2009

DOI:https://doi.org/10.1103/PhysRevB.81.012502

©2010 American Physical Society

Authors & Affiliations

A. Zazunov1, A. Levy Yeyati2, and R. Egger1

  • 1Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
  • 2Departamento de Física Teórica de la Materia Condensada C-V, Universidad Autónoma de Madrid, E-28049 Madrid, Spain

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Issue

Vol. 81, Iss. 1 — 1 January 2010

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