Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 4: Transport: Quantum Dots, Quantum Wires, Point Contacts I (TT jointly with O)
O 4.9: Talk
Monday, March 31, 2014, 11:45–12:00, BEY 81
Unconventional superconductivity in quantum dot systems — Björn Sothmann1, •Stephan Weiss2, Michele Governale3, and Jürgen König1 — 1Departement de Physique Theorique, Universite de Geneve, Switzerland — 2Theoretische Physik, Universität Duisburg-Essen and CENIDE, Germany — 3School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand
Conventional superconductivity of electrons is well described in terms of the BCS theory. Fermi statistics dictates the overall symmetry of e.g. the order parameter. The single ingredients could take either symmetric or antisymmetric properties, hence spin as well as spatial degrees of freedom and time might independently change sign and unconventional pairing amplitudes emerge [1]. We show how quantum dot setups may be used to create unconventional pairing between electrons.
Brought into proximity to a conventional SC, Cooper pairs tunnel into the double (quadrupel)-quantum dot (DQD/QDD) system [2,3]. Locally, manipulations of the electronic state is possible by tuning electric and/or magnetic fields. An inhomogeneous magnetic field between the dots breaks the SU(2) symmetry of the spin. This results in nonzero unconventional order parameters. We study the emergence and decay of even/odd singlet and triplet order parameters in different geometries. For DQD and QDD setups spectroscopic properties and signatures of unconventional correlations in the Andreev current are studied.
[1] F. S. Bergeret, et al., Rev. Mod. Phys. 77, 1321 (2005).
[2] M. Governale, et al., Phys. Rev. B 77, 134513 (2008).
[3] J. Eldridge, et al., Phys. Rev. B 82, 184507 (2010).