Possible entanglement of the vortices in dyba2cu3O7 (y1-xprx)ba2cu3O7 coupled heterostructure

• Thermally activated flux motion is studied in proximity coupled multilayers, containing a number N of 24 Angstrom thick DyBa2Cu3O7 layers separated by 96 Angstrom (or more) of(Y1-xPrx)Ba2Cu3O7 alloy (x=0.4, x=0.55). In contrast to ultra-thin decoupled layers, for which we find that the activation energy for flux motion U approximate to=logB (H//c), coupled samples show a cross-over to a power law behaviour U approximate to B–0.5 at magnetic field H*. This characteristic field depends on the anisotropy and decreases as N increases, a behaviour which can be understood in terms of the entanglement of the vortices, resulting in a relative increase of U due to the flux line crossing energy.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

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