Magnetic and magneto-lattice dynamics in GdMn2O5

Abstract

The dynamics of magnetoelectric RMn 2 O 5 crystals (R=Eu and Gd) was studied in the frequency and temperature ranges 20–300 GHz and 5–50 K, respectively. The crystals possessed magnetic and ferroelectric long-range order and had close transition temperatures, T N, C ≃36 and 30 K for R=Eu and Gd, respectively. Mixed magneto-lattice excitations were observed in GdMn 2 O 5 ; the excitations were most intense near the transition temperature T ≃30 K at frequencies close to the antiferromagnetic resonance frequencies of the Mn subsystem. Along with the antiferromagnetic resonance of the Mn subsystem, the ferromagnetic resonance of the Gd subsystem was observed in GdMn 2 O 5 in an external magnetic field. No such dynamics was characteristic of EuMn 2 O 5 .