The transition from vortex liquid to vortex slush in YB2Cu3Oy superconductors

The phase transition from vortex liquid to vortex slush has been confirmed in resistance measurements for YBCO crystal superconductors, on the basis of scaling analysis. The temperature dependence of the resistivity under various magnetic fields collapses onto two branches in the scaling behaviour, associated with the vortex slush and the vortex liquid states. The lower branch, for temperatures below the transition point, has a negative curvature, while the upper one shows a plateau above the transition point. The critical exponents are estimated from the scaling result. The phase diagram in the H–T plane is presented and compared with previous reports.