High-resolution optical spectroscopy and modeling of spectral and magnetic properties of multiferroic ErFe3(BO3)(4)

M. N. Popova, E. P. Chukalina, D. S. Erofeev, A. Jablunovskis, I. A. Gudim, and B. Z. Malkin. PHYSICAL REVIEW B. DOI:https://doi.org/10.1103/PhysRevB.101.205108

We carried out the high-resolution broadband temperature-dependent polarized optical spectroscopy and theoretical studies of $ErF e_{3} {(B O_{3})}_{4}$ single crystals in the paramagnetic and antiferromagnetic $(T < T_{N} = 39 K)$ phases. On the basis of the experimentally determined 45 crystal-field (CF) levels of $E {r^{3}}^{+}$ ions at sites with the $C_{2}$ point symmetry, CF calculations were performed, a set of physically grounded CF parameters was obtained and used to model the temperature dependences of the Er magnetic moments measured in neutron-scattering experiments, as well as the magnetic susceptibility and magnetization of the compound; the contributions of the quasi-one-dimensional iron magnetic subsystem were calculated in the frame of the previously developed self-consistent four-particle cluster model. The modeling strongly supports an easy-plane collinear structure of iron magnetic moments and excludes earlier proposed additional magnetic phase