Antiferromagnetic resonance in crystalline PrFe3(BO3)4

Experimental AFMR studies of crystalline PrFe3(BO3)4 over a wide frequency range of 10–143 GHz at a temperature of 4.2 K have been carried out. The high-frequency properties of praseodymium ferroborate are well described in terms of a model of a two-sublattice antiferromagnet with an “easy axis” anisotropy. An energy gap of 134.3 ± 0.5 GHz is determined and the magnitude of the effective magnetic anisotropy field is estimated to be 1.9 ± 0.1 kOe. An analysis indicates that the spin-orientational phase transition in this compound is a first order transition.