Phys. Rev. Lett. 92, 097002 (2004) [4 pages]Glassy Vortex Dynamics Induced by a Random Array of Magnetic Particles above a SuperconductorReceived 2 September 2003; published 4 March 2004 The magnetic relaxation of a Nb film covered with a random array of permalloy particles has been studied using various procedures. When the sample undergoes a field-cooled process, the magnetic relaxation becomes logarithmic in time. The relaxation rate is nearly temperature independent at low temperature and characteristic glassy dynamics—aging and memory effects—are observed. These results are interpreted as the consequence of pinning by the statistical variation of the number of nanoparticles within the area of a vortex core. © 2004 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.92.097002
DOI:
10.1103/PhysRevLett.92.097002
PACS:
74.25.Qt, 74.78.Db, 75.50.Lk, 75.75.+a
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