Vortex Melting and Superconducting Transition in High-Tc Oxides

Abstract

The existence of an order-disorder phase transition which can be induced in the vortex matter of type II superconductors by increasing T or H is now well established. At high temperatures the location of the so-called vortex melting line can then be shifted either downwards or upwards by introducing point or columnar defects. We show that the introduction of the latter in (K,Ba)BiO3 single crystals has also a strong influence on the transition from superconducting to normal state.