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A study was conducted to examine the microscopic film structure and the magnetic hysteresis of Mg[B.sub.2] thin films synthesized by using hybrid physical chemical vapor deposition (HPCVD) which do not show dendritic avalanche compared to those prepared by pulsed laser deposition (PLD). The critical current density ([J.sub.c]), estimated from the magnetic hysteresis based on the Bean's critical-state model which showed a much higher [J.sub.c] in the PLD film than in a HPCVD film indicated higher vortex pinning in the PLD film.

The current-carrying capability of high quality epitaxial Mg[B.sub.2] films prepared by using the hybrid physical-chemical vapor deposition method is studied by using transport measurement in nanobridge constrictions and magnetization measurement. An extremely high self-field critical current density is observed, which has shown an excellent current-carrying capability in these films.

Melt-textured growth method enables the preparation of DyBa2Cu3O4 crystals. Virgin magnetization curves of these crystals exhibit an on-parameters scaling behavior in the temperature range from 10 to 85 K. Temperature influences the irreversibility of magnetization. Extended Bean model explains the scaling behavior of these crystals.