Terahertz-infrared spectroscopy of Ti4+-doped M-type barium hexaferrite

Alyabyeva, Liudmila, Samvel Yegiyan, Victor Torgashev, Anatoly S. Prokhorov, Denis Vinnik, Svetlana Gudkova, Dmitry Zherebtsov, Martin Dressel, and Boris Gorshunov. "Terahertz-infrared spectroscopy of Ti4+-doped M-type barium hexaferrite." Journal of Alloys and Compounds 820 (2020): 153398.

Abstract

We report on the first detailed investigations of the terahertz-infrared dielectric response of potential multiferroic single crystalline Ti-doped M-type barium hexagonal ferrite, BaFe12-xTixO19, with concentrations of the dopant above (x = 1.15) and below (x = 0.62) the critical concentration that corresponds to changes of the charge compensation mechanism. Employing terahertz time-domain spectroscopy and Fourier-transform infrared spectroscopy, we performed measurements of the spectra of complex dielectric permittivity ε*(ν) = ε′(ν)+iε"(ν) at frequencies ν = 2-8000 cm−1 (0.06–240 THz) and in the temperature interval T = 10–300 K. The effect of aliovalent cation substitution on the low-energy response of barium hexaferrite is analyzed and discussed. A rich set of polarization- and temperature-dependent excitations is observed and their origin assigned to the electronic transition within the ground state 5E of the four-fold coordinated divalent iron, to relaxational dynamics of domains, and to phonon resonances.

for full paper see https://www.sciencedirect.com/science/article/abs/pii/S0925838819346444

"At terahertz frequencies (7- 100 cm-1, resolution 1.2 cm-1), spectra of real and imaginary parts of the complex dielectric permittivity were directly (without using Kramers-Kronig analysis) determined with the help of terahertz time-domain spectrometers TeraView TPS 3000"