Cj. Vanderbeek et al., DISAPPEARANCE OF THE FORCE-FREE CURRENT CONFIGURATION AT THE FIRST-ORDER VORTEX LATTICE PHASE-TRANSITION IN YBA2CU3O7-DELTA SINGLE-CRYSTALS, Physica. C, Superconductivity, 282, 1997, pp. 1953-1954
The anisotropy in the transverse AC susceptibility of YBa2Cu3O7-delta
single crystals, induced by the periodic appearance of a force-free cu
rrent configuration upon rotation of a superimposed DC field in the cr
ystal plane, disappears at the vortex phase transition, indicating the
loss of the vortex lines' stability against mutual cutting.