Faraday rotation of pure and substituted cobalt ferrite single crystals

Abstract

Faraday rotation measurements have been performed on single crystals of CoFe 2O 4, CoFe 2− x Al x O 4 ( x = 0.27) and Co 1− y Cd y Fe 2O 4 ( y = 0.25) at 1150 nm wavelength as a function of temperature (5⩽ T⩽580 K). The magnetic field up to 2 T was applied along two crystallographic orientations [100] and [111]. Results show a very strong anisotropy of magnetic origin due to Co 2+ and/or tetrahedral site occupancy. Crystal structure determinations show that Al 3+ substitution in pure CoFe 2O 4 increases the tetrahedral Co 2+ amount, leading to a strong decrease of the absolute FR.