**GINZBURG-LANDAU THEORY OF VORTEX PHASE DIAGRAM**

**IN LAYERED TYPE II SUPERCONDUCTOR**

**RYUSUKE IKEDA**

Department of Physics, Kyoto University, Kyoto 606-8502, JAPAN

Various macroscopic phenomena seen in high temperature superconductors (HTSC) under nonzero magnetic fields have inspired much interest in studying the phase diagram of vortex states of three dimensional (3D) layered type II superconductors. Experimentally, thermodynamic and transport phenomena have been intensively examined mainly in YBCO \[1-3\] and BSCCO \[4\]. The resistive broadening \[5\] in the so-called vortex liquid regime below the crossover line $H_{c2}(T)$ is common to these materials with strong fluctuation effect and is well described in terms of the non-Gaussian superconducting fluctuation theory\[6\]. Since, on approaching a phase transition, macroscopic behaviors tend to become insensitive to microscopic details of each material, one expects that the phase diagram itself should be qualitatively the same between these materials. However, recent data \[7-10\] in YBCO seem to have shown some details of transition lines in real systems with pinning disorders which have been unseen in BSCCO. It is important to find how such phenomena [*apparently*]{} dependent on the materials are explained within a single GL theory.

Theoretically, the phase diagram of vortex states has been tackled from two different points 