Field-induced SDW and integer quantum Hall effect in anisotropic three-dimensional electron systems

In order to realize Hofstadterʹs butterfly and Quantum Hall effect (QHE) in 3D systems as proposed previously (Phys. Rev. Lett. 86 (2001) 1062), we consider a system that has the field induced spin density wave (FISDW) phases. By extending the 2D FISDW model for an organic conductor to 3D, we show that there exists a series of FISDW phases peculiar to 3D in the phase diagram against (By,Bz). The quasi-particle spectrum is found to be indeed fractal.