The Vortex Glass-Liquid Transition in Fe1.02Se Crystal

The vortex-glass (VG) to vortex-liquid (VL) transition is studied in flux-grown Fe1.02Se crystal with nanosized hexagonal phase inclusions. These non-superconducting impurities effectively pin the vortices and shift lightly the irreversibility line to higher fields and temperatures in comparison with single crystal. It is shown that the interplay between vortex pinning and thermal fluctuations enable the observation of VG-VL transition. The existence of this transition was proved by the scaling presentation of current-voltage characteristics at two different magnetic fields. The obtained scaling parameters are practically field independent. The values of the dynamic z exponent are in the range predicted by the VG model, while the values of static ν exponent are a little smaller. This is not considered as a lack of the universality of the model, but rather as a consequence of the type of pinning and special domain morphology of the crystal resembling the granularity in polycrystalline s