Investigation of the iron borates DyFe3(BO3)4 and HoFe3(BO3)4 by the method of Er3+ spectroscopic probe

Temperature-dependent high-resolution optical spectra of the Er3+ probe ion in DyFe3(BO3)4 and HoFe3(BO3)4 are reported. The data provide the temperature of magnetic ordering and direction of the Fe3+ magnetic moments. Both compounds order magnetically at TN=39±1 KTN=39±1 K. The magnetic structure of DyFe3(BO3)4 is of the easy-axis type, while that of HoFe3(BO3)4 is of the easy-plane type. The role of anisotropic interactions between the iron and the rare-earth subsystems is discussed.