The magneto-optical activity of rare-earth ion in Y-substituted erbium and neodymium iron garnets

Abstract

The magnetic and magneto-optical (MO) properties of Er x Y 3− x Fe 5O 12 ( x = 0.4, 1.0, 1.5, 2.5 and 3.0) (ErYIG) and Nd x Y 3− x Fe 5O 12 ( x = 0.5, 0.96, 1.39 and 1.72) (NdYIG) single crystals have been presented. Faraday rotation (FR) spectra obtained in energy region 5500–13,000 cm −1 for the erbium garnets and in energy region 6000–17,000 cm −1 for the neodymium garnets with a high optical resolution have been presented here, in contrast to other researches of the FR performed only at 1152 nm (8696 cm −1). The investigations at 5, 130 and 295 K temperatures under magnetic field up to 20 kOe applied parallel to the [1 1 1] crystallographic axes of the crystals have been provided. Anomalous great MO activity is the result of joint action of similar in sign and approximately equal in quantity of paramagnetic and diamagnetic mechanisms in NdYIG. It has been shown that proportional to magnetic field and independent of temperature contribution of the mixing of the ground state multiplets mechanism exceeds paramagnetic contribution. Concentration dependence of MO coefficients confirms one-ion nature of MO activity of ErYIG.