New effects of the electron—phonon interaction in dielectrics

We have studied the electron—phonon interaction (EPI) in multiferroic ${\text PrFe}_3({\text BO}_3){}_4$ using far-infrared (terahertz) reflection and theoretical simulation. A specific feature of ${\text PrFe}_3({\text BO}_3){}_4$ is that the 4f electronic excitation of the ${\text Pr}^{\,3+}$ ion falls into a range between the longitudinal (LO) and transverse (TO) phonon frequencies. Inversion of the electronic oscillator occurs: its LO frequency becomes smaller than the TO frequency. As temperature diminishes, a coupled electron—phonon mode emerges, and a new effect is observed: the reststrahlen band corresponding to a nondegenerate phonon mode splits. Another effect caused by the EPI is the existence of a gap in the spectrum of electronic excitations of a stoichiometric rare-earth easy-axis antiferromagnet placed into an arbitrarily weak external magnetic field directed along the easy magnetization axis.

Keywords: inverted electronic oscillator, electron—phonon interaction, coupled electron—phonon mode, bifurcations in magnetic field, terahertz spectroscopy
PACS: 63.20.kd, 71.70.−d, 75.50.Ee, 75.85.+t, 78.20.Bh, 78.30.−j (all)
DOI: 10.3367/UFNe.2018.06.038413
URL: https://ufn.ru/en/articles/2019/3/f/
Web of Science

000469214700006
Scopus

2-s2.0-85069543197
ADS NASA

2019PhyU...62..275P
Citation: Popova M N, Boldyrev K N "New effects of the electron—phonon interaction in dielectrics" Phys. Usp. 62 275–281 (2019)

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@article{Popova:2019,
	author = {M. N. Popova and K. N. Boldyrev},
	title = {New effects of the electron—phonon interaction in dielectrics},
	publisher = {Physics-Uspekhi},
	year = {2019},
	journal = {Phys. Usp.},
	volume = {62},
	number = {3},
	pages = {275-281},
	url = {https://ufn.ru/en/articles/2019/3/f/},
	doi = {10.3367/UFNe.2018.06.038413}
}

Received: 12th, August 2018, accepted: 20th, June 2018

Оригинал: Попова М Н, Болдырев К Н «Новые эффекты электрон-фононного взаимодействия в диэлектриках (к 50-летию Института спектроскопии РАН)» УФН 189 292–298 (2019); DOI: 10.3367/UFNr.2018.06.038413