U. Welp et al., THERMODYNAMIC EVIDENCE FOR A FLUX-LINE-LATTICE MELTING TRANSITION IN YBA2CU3O7-DELTA, Physical review letters, 76(25), 1996, pp. 4809-4812
Moving- and stationary-sample SQUID magnetometry indicates discontinuo
us jumps of the magnetization of an untwinned single crystal of YBa2Cu
3O7-delta. The location of these jumps in the H-T plane coincides with
the location of the resistive drops measured on the same sample. Thes
e results demonstrate the existence of a first-order melting transitio
n of the flux line lattice in YBa2Cu3O7-delta.