Dynamics of vortices pinned by columnar defects in YBa₂Cu₃0₇ crystals

We have studied vortex dynamics in YBa2Cu307 crystals containing columnar defects (oriented.L to Cu-O planes), formed by 1 GeV Au-ions. The decay rate -dlnjldblt of persistent current j has a large peak near T = 40 K for H = 1 T. Higher fields suppressed the height and position of this peak, which disappeared for H > Bφ, the matching field. Analyzing the pinning energy shows regimes with several modes of pinning.