In-plane magnetic field dependence of intrinsic Josephson junctions in Tl-Ba-Ca-Cu-O thin films

We have fabricated intrinsic Josephson bridges using Tl-Ba-Ca-Cu-O thin fil ms grown on vicinal lanthanum aluminate substrates, Measurements of the loc k-in transition allow us align a magnetic field of up to 4T with the copper oxide planes to better than 0.3 degrees. This allows us to study the dynam ics of Josephson fluxons in the films, For fields above 1.4T and at low cur rents we observe Josephson flux creep. Above a field-dependent threshold cu rrent we observe free flow of the fluxons with a flux-flow resistance which is proportional to field. The fluxons reach a field-independent velocity b efore the jump to the quasiparticle branch occurs. Our results suggest that the development of a sub-mm-wave oscillator using these bridges will requi re sub-micron patterning.