  The Faraday rotation and magneto-optical absorption spectral measurements
were conducted to reveal the full-magnetization process and map out a magnetic
phase diagram of a typical geometrical frustrated magnet, ZnCr2O4, by using the
electromagnetic flux compression method in ultra-magnetic fields up to 600 T. A
fully polarized ferromagnetic phase is observed in which the absorption spectra
associated with an exciton-magnon-phonon transition disappears. Furthermore,
prior to the fully polarized ferromagnetic phase above 410 T, we found a novel
magnetic phase above 350 T followed by a canted 3:1 phase.
