An optical faraday rotation technique for the determination of magnetic relaxation times

A technique is described for the measurement of macroscopic magnetic relaxation times in crystals using the optical Faraday rotation as a monitor of the magnetization. The method is applied to the paramagnetic Eu²⁺ion in CaF2:Eu²⁺at cryogenic temperatures. In this experiment the crystal is placed between a crossed polarizer and analyzer and subjected to a pulsed magnetic field. The transmitted light from a CW argon-ion laser gives a direct indication of the relaxation time.