Superconductivity in layered materials with intralayer and interlayer couplings

A study of the superconductivity of layered materials is reported. We treat very thin layers and assume two interactions, intralayer and interlayer. A two-component Ginzburg-Landau equation is derived taking into account two types of order parameters. $T_c$ is raised by the cooperation of the two interactions. $H_{c2}$ shows anisotropic behavior not only due to the anisotropy of the one-electron state but also due to the anisotropy of the pairing interaction.