paper

Field-dependent Vortex Pinning Strength in a Periodic Array of Antidots

arXiv:cond-mat/0301118 · doi:10.1103/PhysRevB.67.064502

Abstract

We explore the dynamic response of vortex lines in a Pb thin film with a periodic array of antidots by means of ac-susceptibility measurements. For low drive field amplitudes, within the Campbell regime, vortex motion is of intra-valley type and the penetration depth is related to the curvature of the pinning potential well, . For dc-fields below the first matching field , reaches its highest value associated with a Mott Insulator-like phase where vortex lines are strongly localized at the pinning sites. For , the response is mainly due to the interstitial vortices and drops to smaller values as expected for this metallic-like regime. Strikingly, for , we observe that reduces further down. However, for , a reentrance in the pinning strength is observed, due to a specific configuration of the flux line lattice which strongly restricts the mobility of vortices. We present a possible explanation for the measured dependence based on the different flux line lattice configurations.

5 pages, to be published in Phys. Rev. B

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