We carried out the high-resolution broadband temperature-dependent polarized optical spectroscopy and theoretical studies of $\mathrm{ErF}{\mathrm{e}}_3{\left(\mathrm{B}{\mathrm{O}}_3\right)}_4$ single crystals in the paramagnetic and antiferromagnetic $\left(T<T_N=39\mathrm{K}\right)$ phases. On the basis of the experimentally determined 45 crystal-field (CF) levels of $\mathrm{E}{{\mathrm{r}}^3}^{+}$ 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.

• Received 8 March 2020
• Accepted 9 April 2020

DOI:https://doi.org/10.1103/PhysRevB.101.205108