SPECTROSCOPY OF MN4-FIELD( DOPED GADOLINIUM GALLIUM GARNET IN HIGH MAGNETIC)

The R-lines of the Mn4+ fluorescence, associated with 2E --> 4A2 trans itions in gadolinium gallium garnet exhibits large broadening as compa red with other ions with d3 shell. The laser excitation and fluorescen ce spectra without magnetic field show that this is partially inhomoge neous broadening related to presence of charge-compensating Ca2+ ions. Remaining part of the broadening is due to antiferromagnetic exchange interaction between Mn4+ and surrounding them six Gd3+ ions. The high magnetic field up to 20 T has been used to resolve the spectra broade ned by spin-spin interaction. The estimated value of the spin-spin exc hange constant is equal to J almost-equal-to 1.9 cm-1.