Antiferromagnetic resonance study of the magnetic structure of Nd_0.75Dy_0.25Fe₃(BO₃)₄ Available to Purchase

The effect of replacing Nd³⁺ ions with Dy³⁺ ions on the resonance properties of Nd_0.75Dy_0.25Fe₃(BO₃)₄ is studied. The antiferromagnetic resonance (AFMR) method is used to detect an easy axis-easy plane magnetic spin-reorientation phase transition owing to competing exchange interactions of Nd–Fe and Dy–Fe, and the frequency-field dependence of the AFMR spectrum before and after the phase transition is studied. At 4.2 K, the detected resonance spectra in the H||c direction are AFMR modes of iron, and their frequency-field dependences correspond to easy-axis (H < 15 kOe) and easy-plane (H > 16 kOe) magnetic structures with magnon excitation energy gaps of 77.2 and 100.3 GHz, respectively. The effective magnetic anisotropies responsible for these gaps are 0.7 and 1.2 kOe, respectively. Substitution by Dy³⁺ ions in crystalline Nd_0.75Dy_0.25Fe₃(BO₃)₄ in the paramagnetic region produces an additional static internal field owing to polarization, which leads to a shift in the resonance field of the EPR absorption line and a change in the g-factor of the Fe³⁺ ions.