Bifurcations observed in the spectra of coupled electron-phonon modes in multiferroic $PrFe_3(BO_3)_4$ subjected to a magnetic field

TL;DR

This study investigates bifurcations in coupled electron-phonon modes in a multiferroic antiferromagnet under magnetic fields, revealing field-dependent spectral features explained by a theoretical model of coupled modes.

Contribution

It demonstrates the observation of bifurcations in coupled electron-phonon spectra in PrFe3(BO3)4 and models these effects using a field-independent coupling constant within a theoretical framework.

Findings

Bifurcations in coupled modes observed under magnetic field.

Spectral behavior explained by a coupled electron-phonon mode model.

Electron-phonon interaction constant found to be field-independent.

Abstract

We report on bifurcations effect mediated by the electron-phonon coupling in a concentrated rare-earth-containing antiferromagnet, observed in the spectra of coupled $4f$-electron-phonon modes under the influence of an external magnetic field. The effect was observed in the low-temperature far-infrared (terahertz) reflection spectra of a multiferroic easy-axis antiferromagnet $PrFe_3(BO_3)_4$ in magnetic fields $\textbf{B}_{ext}||c$. Both paramagnetic and magnetically ordered phases (including a spin-flop one) were studied in magnetic fields up to 30 T. We show that the field behavior of the coupled modes can be successfully explained and modeled on the base of the equation derived in the frame of the theory of coupled electron-phonon modes, with the same field-independent electron-phonon interaction constant $|W| = 14.8 cm^{-1}$.