Spin–Phonon and Electron–Phonon Interactions in Multiferroic GdFe $$_{3}$$ 3 (BO $$_{3}$$ 3 ) $$_{4}$$ 4 and TbFe $$_{3}$$ 3 (BO $$_{3}$$ 3 ) $$_{4}$$ 4 Evidenced by IR Reflection Spectroscopy

Abstract

We study temperature-dependent polarized reflection spectra of multiferroic GdFe\(_{3}\)(BO\(_{3})_{4}\) and TbFe\(_{3}\)(BO\(_{3})_{4}\) single crystals. Signatures of spin–lattice interactions in both compounds and of a formation of the electron–phonon coupled mode in TbFe\(_{3}\)(BO\(_{3})_{4}\) are discussed.