Direct Transition from Bose Glass to Normal State in the [Formula presented] Superconductor

The introduction of columnar defects in [Formula presented] single crystals shifts both the irreversibility and thermodynamic transition lines, respectively, deduced from ac susceptibility (and/or transport) and specific heat measurements, upwards. This shift can be attributed to the defect-induced decrease of the difference ([Formula presented]) between the free energies in the superconducting and the normal states, assuming that the position of the superconducting transition is given by the condition [Formula presented]. This criterion also perfectly reproduces the influence of the angle between the tracks and the external field. This result suggests that no vortex liquid phase exists in this system.