Thermodynamic and optical properties ofNdCr3(BO3)4

Abstract

We present magnetization and specific heat data as well as optical spectra of $\mathrm{Nd}{\mathrm{Cr}}_{3}{(\mathrm{B}{\mathrm{O}}_{3})}_{4}$ single crystals. At ${T}_{N}=8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, the magnetic and specific heat data imply long-range antiferromagnetic spin order of the ${\mathrm{Cr}}^{3+}$ subsystem. This observation is corroborated by the spectroscopic studies since in the ordered state the ${\mathrm{Nd}}^{3+}$ Kramers doublets are split by the internal staggered magnetic field. The splitting is also visible in a Schottky anomaly at the specific heat. In the spin-ordered phase, we find a staggered magnetic field at the Nd sites of $35\phantom{\rule{0.3em}{0ex}}\mathrm{kG}$ at $1.8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The values ${\ensuremath{\lambda}}_{\mathrm{Nd}\text{\ensuremath{-}}\mathrm{Cr}}=3.9\phantom{\rule{0.3em}{0ex}}\mathrm{kG}∕{\ensuremath{\mu}}_{B}$ and ${\ensuremath{\lambda}}_{\mathrm{Cr}\text{\ensuremath{-}}\mathrm{Cr}}=29.4\phantom{\rule{0.3em}{0ex}}\mathrm{kG}∕{\ensuremath{\mu}}_{B}$ are obtained for the molecular-field constants of the Nd-Cr and the Cr-Cr interactions, respectively. The analysis of the magnetic susceptibility data points to the easy-plane type of the antiferromagnetic order. Several experimental manifestations of the low dimensionality of the title compound are mentioned.