Observation of periodic vortex pinning-induced by Bitter decoration

In this paper we report on a type of vortex pinning, Bitter pinning. In thi s technique, a vortex lattice in a type II superconductor, NbSe2, is decora ted with magnetic particles Which form dumps on the surface of the sample w here the vortices exit. Because of the van der Waals forces, these magnetic dots stay well fixed after the sample is returned to room temperature. We present data showing that these patterns can act as pinning sites for vorti ces in subsequent experiments. This method allows one, in: a simple and eff ective way, to produce periodic, quasiperiodic, or disordered pinning struc tures-for Static: and dynamic vortex experiments. [S0163-1829(99)51342-8].