Splitting of a nondegenerate phonon mode in PrFe3(BO3)4: 4f crystal-field level between TO and LO phonon frequencies

Abstract

A new effect originating from the crystal-field-excitation - phonon coupling was observed (in the far infrared spectra of a multiferroic PrFe3(BO3)4). The reststrahlen band corresponding to the A2 symmetry nondegenerate phonon mode near 50 cm-1 (1.5 THz) splits into two bands at about 100 K, well above TN = 32 K. These bands shift and narrow progressively with further lowering the temperature, demonstrating pronounced peculiarities at TN. The observed effects were explained by an interaction of the A2 phonon mode with the 4f crystal-field electronic excitation of Pr3+ whose frequency falls into the TO - LO frequency region of the phonon mode. Inversion of the TO and LO frequencies for the electronic excitation and a formation of coupled electron-phonon modes are discussed. Fitting of the TO frequency vs temperature experimental plots by theoretical curves revealed the value 14.6 cm-1 for the electron-phonon coupling constant.

5 pages, 3 figures

References in corpus (2)

• Raman scattering from phonons and magnons in RFe3)BO3)4
• Magnetoelectric Effect and Spontaneous Polarization in HoFe${}_3$(BO${}_3$)${}_4$ and Ho${}_{0.5}$Nd${}_{0.5}$Fe${}_3$(BO${}_3$)${}_4$

Cited by in corpus (5)

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• Infrared study of lattice dynamics and spin-phonon and electron-phonon interactions in multiferroic TbFe3(BO3)4 and GdFe3(BO3)4
• Lattice dynamics and a magnetic-structural phase transition in the nickel orthoborate $N{i}_3(B{O}_3{)}_2$
• Emergent Vibronic Excitations in the Magnetodielectric Regime of ${\text{Ce}}_2{\text{O}}_3$: Raman Scattering Studies
• Bifurcations observed in the spectra of coupled electron-phonon modes in multiferroic $PrF{e}_3(B{O}_3{)}_4$ subjected to a magnetic field