Evidence for diverging barriers in the disordered vortex solid in the (K,Ba)BiO(3) superconducting oxide.
Vortex dynamics has been investigated in the cubic (K,Ba)BiO (3) superconductor using ac susceptibility measurements on a large frequency range (0.03 Hz<omega<60 kHz). Power law diverging barriers have been obtained on both sides of the order-disorder transition line. The mu exponent remains close to 5/2 (elastic creep value) in some part of the disordered phase and finally decreases at high temperature and/or high field, in good agreement with the recent plastic collective creep theory [J. Kierfeld, H. Nordborg, and V. M. Vinokur, Phys. Rev. Lett., 85, 4948 (2000)].
Joumard
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Laboratoire d'Etudes des Propriétés Electroniques des Solides, Centre National de la Recherche Scientifique, BP 166, 38042 Grenoble Cedex 9, France.
Klein
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T
Marcus
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