Low-temperature features of Raman spectra below magnetic transitions in multiferroic Ho1-xNdxFe3(BO3)(4) and Sm1-yLayFe3(BO3)(4) single crystals

Raman spectra changes in multiferroic Ho_1–xNd_xFe₃(BO₃)₄ (x = 0, 0.25, 0.5, 0.75) and Sm_1–yLa_yFe₃(BO₃)₄ (y = 0, 0.75) single crystals at low temperatures have been analyzed. The anomalies corresponding to the phase transition of the second order have been detected at the temperatures of magnetic phase transitions, being consistent with previously reported results of the magnetization study. A number of anomalies in the temperature dependences of the spectral lines associated with the occurrence of magnetic order. A mode corresponding to two-magnon scattering was revealed. Comparison of the features of low-temperature low-frequency spectra of solid solutions Ho-Nd and Sm-La has been carried out.