The Effect of Spin Fluctuations on the Exchange Field in Pr:YIG Crystal at Low Temperature

Based on the temperature dependence of spin fluctuations of magnetic ions, the exchange field H_exch acting on the rare-earth ions in Pr-substituted yttrium iron garnet (Pr:YIG) is modified, which is expressed as H_exch=n₀(1+γT+βe^ωT)M_YIG. By means of the improved exchange field, the magnetic and magneto-optical properties of Pr:YIG are calculated. The calculated results are in good agreement with the experimental data in the temperature range of 4.2–300 K. Our study implies that the spin fluctuations of magnetic ions have an important influence on the magnetic and magneto-optical properties of Pr:YIG at low temperature.