The complex resistivity ρ^ of the vortex system in YBa2Cu3O7 has been measured from 0.2 to 20 MHz. The solid phase below the transition field Hm is characterized by strong dispersion in ρ^. At the transition, an abrupt decrease of the reactance Im ρ^ is observed. We show that this is caused by a collapse of the shear modulus c66 at Hm. The experiment provides firm evidence for a first-order melting transition.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)