Nearly field-independent in-plane vortex solid-to-liquid transition in thec-axis resistivity of oxygen deficient single crystals of YBa2Cu3O7-delta - art. no. 060503

The c-axis resistivity has been measured in oxygen deficient single crystal s of YBa2Cu3O7-delta (anisotropy gamma approximate to 24-29) with the magne tic field B accurately aligned parallel to the ab plane. An almost field-in dependent vortex solid-to-liquid transition is observed at high fields in c ontrast to the usual field-dependent one, which is recovered for a small mi salignment between B and ab. This observation challenges previous interpret ations of the same effect in the ab resistivity as coming from a smectic vo rtex state or a decoupling of the superconducting planes.