Influence of magnet size on magnetically engineered field-induced superconductivity

W. Gillijns, M. V. Milošević, A. V. Silhanek, V. V. Moshchalkov, and F. M. Peeters
Phys. Rev. B 76, 184516 – Published 20 November 2007

Abstract

We investigate experimentally and theoretically the superconducting properties of an Al thin film covering a periodic array of CoPt magnetic disks with out-of-plane magnetization for different radii of the magnetic disks and constant period of the magnetic lattice. The presence of the arrays of magnetic dots leads to a quantized displacement of the normal/superconducting phase boundary along the magnetic field axis, with each step corresponding to a flux-quantum per unit cell of the magnetic lattice. We demonstrate that this so-called field-induced superconductivity is strongly dependent not only on the chosen magnetic material and its magnetization M but also on the radius R of the constructed magnetic disks. Since field-induced superconductivity is directly linked to the nucleation of vortex-antivortex (V-AV) pairs, a theoretical MR equilibrium phase boundary is presented, delimiting regions of different numbers of induced V-AV pairs per magnet. A good qualitative and quantitative agreement is found between theory and experiment.

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  • Received 27 July 2007

DOI:https://doi.org/10.1103/PhysRevB.76.184516

©2007 American Physical Society

Authors & Affiliations

W. Gillijns1,*, M. V. Milošević2,3, A. V. Silhanek1, V. V. Moshchalkov1,†, and F. M. Peeters3,‡

  • 1INPAC-Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and Magnetism and Pulsed Fields Group, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
  • 2Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
  • 3Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium

  • *werner.gillijns@fys.kuleuven.be
  • victor.moshchalkov@fys.kuleuven.be
  • francois.peeters@ua.ac.be

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Issue

Vol. 76, Iss. 18 — 1 November 2007

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