Flux-flow resistivity in UPt3: Evidence for nonsingular vortex-core structure - art. no. 020510

We have investigated the core structure of B-phase vortex lines in two clea n UPt3 crystals, using flux-flow dissipation as the probe. The flux-flow re sistivity is determined from the skin depth of the high-frequency oscillati ons of the vortex lines in the pinned state. With (H) over cap perpendicula r to (c) over cap our data agree with the previously established scaling la w of the moderately clean limit with anisotropic gap. When (H) over cap par allel to(c) over cap, the resistivity is three times larger. We interpret t his increase as evidence for a vortex-core structure with two length scales , as predicted for UPt3 with a two-component order parameter.