Phys. Rev. B 67, 140505(R) (2003) (4 pages)

Decoupling and decommensuration in layered superconductors with columnar defects

A. Morozov and B. Horovitz

Department of Physics and Ilze Katz Center for Nanotechnology, Ben Gurion University, Beer Sheva 84105, Israel

P. Le Doussal

CNRS-Laboratoire de Physique Théorique de l'Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France

(Received 31 October 2002; published 28 April 2003)

We consider layered superconductors with a flux lattice perpendicular to the layers and random columnar defects parallel to the magnetic field B. We show that the decoupling transition temperature T_d, at which the Josephson coupling vanishes, is enhanced by columnar defects by an amount T_d/T_d~B². Decoupling by increasing field can be followed by a reentrant recoupling transition for strong disorder. We also consider a commensurate component of the columnar density and show that its pinning potential is renormalized to zero above a critical long-wavelength disorder. This decommnesuration transition may account for a recently observed kink in the melting line. ©2003 The American Physical Society

PACS: 74.50.+r, 64.60.Cn, 74.25.Qt       

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