Persistent currents in mesoscopic rings and conformal invariance |
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Authors: | M Henkel D Karevski |
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Institution: | (1) Laboratoire de Physique des Matériaux (Unité Mixte de Recherche CNRS No. 7556), Université Henri Poincaré Nancy I, BP 239, 54506 Vandoeuvre-lès-Nancy Cedex, France, FR |
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Abstract: | The effect of point defects on persistent currents in mesoscopic rings is studied in a simple tight-binding model. Using an
analogy with the treatment of the critical quantum Ising chain with defects, conformal invariance techniques are employed
to relate the persistent current amplitude to the Hamiltonian spectrum just above the Fermi energy. From this, the dependence
of the current on the magnetic flux is found exactly for a ring with one or two point defects. The effect of an aperiodic
modulation of the ring, generated through a binary substitution sequence, on the persistent current is also studied. The flux-dependence
of the current is found to vary remarkably between the Fibonacci and the Thue-Morse sequences.
Received: 4 March 1998 / Revised: 20 April 1998 / Accepted: 30 April 1998 |
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Keywords: | PACS 05 20 -y Statistical mechanics - 64 60 -i General studies of phase transitions - 73 23 -b Mesoscopic systems |
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