We report on the high-resolution Fourier spectroscopy study of KY3F10:Pr3+ crystals. The analysis of the transmission and luminescence spectra allowed us to refine and supplement the information on the crystal-field levels of the Pr3+ ion. The value of the hyperfine splitting of the ground state of Pr3+ in the KY3F10 cubic host is estimated. The observed shape of the spectral lines indicates the presence of defects in the sample under study.

The paper reports the first observation of a resolved hyperfine structure in the optical spectra of YVO4:Ho3+ crystal and discusses its possible applications in the remote thermometry. The transmission spectra of YVO4:Ho3+ in the region of 5I6 and 5I7 multiplets of the Ho3+ ion at low temperatures were investigated. The energies and symmetries of crystal-field (CF) levels of these multiplets have been refined. The hyperfine structure was observed for optical transitions from the Gamma 5 CF level at 46.9 cm -1 of the ground multiplet. Deformation splittings were observed for several Gamma 5 states, which can be used for crystal quality control. Magnetic g factors were derived for the Gamma 5 levels. The YVO4:Ho3+ material can be used as a working medium for thermometry over a wide temperature range from two to several hundred Kelvin.

Iron borates NdFe3(BO3)4 and SmFe3 (BO3)4 activated with 1

Infrared absorption spectra of the ErCrO3 crystal in the region of f- f transitions in the Er3+ ion are recorded for the first time. An analysis of high-resolution temperature-dependent spectra reveals a step at T 1pt ' = 47 K on the temperature dependences of the characteristics of spectral lines, in addition to the features at temperatures of magnetic ordering TN = 133 K and spin-reorientation transition T_SR = 9.3 1pt K. This feature can be associated with either a previously unknown phase transition or with local changes in the crystal structure. The shape of the lines at liquid helium temperatures indicates the presence of additional positions for Er3+ ions in the ErCrO3 crystal. Presumably, these are positions near uncontrolled impurities that enter the crystal during its growth by the solution–melt method and form regions with a distorted structure responsible for the occurrence of polarization.

Infrared absorption spectra of the ErCrO3crystal in the region off−ftransitions in the Er3+ion are recorded for the first time. An analysis of high-resolution temperature-dependent spectra reveals a step atT′=47K on the temperature dependences of the characteristics of spectral lines, in addition to the features at temperatures of magnetic orderingTN= 133 K and spin-reorientation transitionTSR=9.3K. This feature can be associated with either a previously unknown phase transition or with local changes in the crystal structure. The shape of the lines at liquid helium temperatures indicates the presence of additional positions for Er3+ions in the ErCrO3crystal. Presumably, these are positions near uncontrolled impurities that enter the crystal during its growth by the solution–melt method and form regions with a distorted structure responsible for the occurrence of polarization.

We report on the high-resolution Fourier spectroscopy study of KY3F10:Pr3+ crystals. The analysis of the transmission and luminescence spectra allowed us to refine and supplement the information on the crystal-field levels of the Pr3+ ion. The value of the hyperfine splitting of the ground state of Pr3+ in the KY3F10 cubic matrix is estimated. The observed shape of the spectral lines indicates the presence of defects in the sample under study.

Iron borates NdFe3(BO3)4 and SmFe3(BO3)4 activated with 1% erbium, with a huntite structure (space symmetry group R32) were investigated by the method of erbium spectroscopic probe. From an analysis of the temperature dependence of the transmission spectra in the region of the 4I15/2→4I13/2 transition in the Er3+ ion, it was found that both studied compounds order antiferromagnetically at TN ≈ 33 K into an easy-plane magnetic structure. No other phase transitions were found.

Iron borates NdFe3(BO3)4 and SmFe3(BO3)4 activated with 1% erbium, with a huntite structure (space symmetry group R32) were investigated by the method of erbium spectroscopic probe. From an analysis of the temperature dependence of the transmission spectra in the region of the 4I15/2→4I13/2 transition in the Er3+ ion, it was found that both studied compounds order antiferromagnetically at TN ≈ 33 K into an easy-plane magnetic structure. No other phase transitions were found.

Iron borates NdFe3(BO3)4 and SmFe3(BO3)4 activated with 1% erbium, with a huntite structure (space symmetry group R32) were investigated by the method of erbium spectroscopic probe. From an analysis of the temperature dependence of the transmission spectra in the region of the 4I15/2→4I13/2 transition in the Er3+ ion, it was found that both studied compounds order antiferromagnetically at TN ≈ 33 K into an easy-plane magnetic structure. No other phase transitions were found.

We report on the high-resolution Fourier spectroscopy study of KY3F10:Pr3+ crystals. The analysis of the transmission and luminescence spectra allowed us to refine and supplement the information on the crystal-field levels of the Pr3+ ion. The value of the hyperfine splitting of the ground state of Pr3+ in the KY3F10 cubic matrix is estimated. The observed shape of the spectral lines indicates the presence of defects in the sample under study.

We report on the high-resolution Fourier spectroscopy study of KY3F10:Pr3+ crystals. The analysis of the transmission and luminescence spectra allowed us to refine and supplement the information on the crystal-field levels of the Pr3+ ion. The value of the hyperfine splitting of the ground state of Pr3+ in the KY3F10 cubic matrix is estimated. The observed shape of the spectral lines indicates the presence of defects in the sample under study.

The magnetic structure is usually determined by the neutron diffraction measurements. However, in the case of complex multisublattice magnetics, this method fails to give an unambiguous result. Here, on the example of multiferroic ${\mathrm{HoFe}}_{3}{({\mathrm{BO}}_{3})}_{4}$, we show that in the case of rare-earth (RE) compounds the right magnetic structure can be determined by additionally using optical spectroscopy and a theoretical analysis based on spectroscopic data. ${\mathrm{HoFe}}_{3}{({\mathrm{BO}}_{3})}_{4}$ demonstrates a series of phase transitions and interesting magnetic and magnetoelectric properties. The available information on the magnetic structure of the compound, necessary for understanding and utilizing these properties, is contradictory. To resolve the existing ambiguities, we apply a combined approach. The high-resolution spectroscopy data deliver a set of the ${\mathrm{Ho}}^{3+}$ crystal-field (CF) levels in the paramagnetic and both easy-plane and easy-axis magnetic phases. These data are used to determine CF and ${\mathrm{Ho}}^{3+}\text{\ensuremath{-}}{\mathrm{Fe}}^{3+}$ exchange parameters and, then, to calculate the temperature dependencies of the magnetic susceptibility tensor of ${\mathrm{HoFe}}_{3}{({\mathrm{BO}}_{3})}_{4}$. Based on these calculations, we suggest an easy-plane antiferromagnetic structure with a collinear arrangement of the Fe spins along the $a$ axis and induced noncolinear moments of magnetically nonequivalent Ho ions. The suggested structure is further confirmed by single-crystal elastic neutron scattering experiments. We argue that specific features of the magnetic properties of RE iron borates isostructural to ${\mathrm{HoFe}}_{3}{({\mathrm{BO}}_{3})}_{4}$ are governed by the energy patterns and the symmetry properties of the wave functions of the lower CF levels of the RE ground multiplet in the crystal field of the ${C}_{2}$ symmetry.

Multifunctional Pr3+:YPO4 single crystals were investigated by high-resolution optical Fourier spectroscopy. The analysis of the transmission and luminescence spectra allowed us to supplement information on crystal-field levels of the Pr3+ ion. Shapes of spectral lines corresponding to transitions from the ground state to the degenerated ?5 crystal-field levels reveal the hyperfine structure and unambiguously point to the presence of random lattice deformations. The experimentally observed line shapes were successfully modeled and the halfwidth of the distribution function of random lattice deformations was determined. The lines with frequencies 4308 cm-1 and 9680 cm-1 are most sensitive to deformations and can be used to control the quality of YPO4 single crystals intended for applications in modern quantum technologies.

The shape and fine structure of lines due to Tm3+ f −f electronic transitions in multifunctional Y3Al5O12 garnet crystals have been studied by high-resolution spectroscopy. The observed inhomogeneously broadened lines have a Lorentzian shape, suggesting that point defects make a predominant contribution to the inhomogeneous broadening. Moreover, YAl antisite defects, which are formed during high-temperature melt growth, produce spectral satellites near the main lines.

We report on the high-resolution spectroscopic study of multiferroic ErFe3(BO3)(4). The energies of all eight Kramers doublets of the ground I-4(15/2) multiplet of the Er3+ ion were determined by the high-resolution I-4(13/2) -> I-4(15)/2 infrared luminescence spectra. The spectroscopically determined temperature dependence of the splitting of the ground Kramers doublet was used to calculate the contribution of the erbium subsystem into the specific heat and the magnetic susceptibility of erbium iron borate. The analysis of the thermodynamic properties based on these calculations allowed us to suggest the domain structure in the easy-plane antiferromagnetically ordered iron subsystem, with two magnetically nonequivalent erbium positions in each domain.

We carried out the high-resolution broadband temperature-dependent polarized optical spectroscopy and theoretical studies of ErFe3(BO3)(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 Er3+ 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.

AbstractHigh-resolution low-temperature absorption spectra in the region of the ^5 I _8 → ^5 I _7, 6, 5, 4, ^5 F _5 transitions in impurity Ho^3+ ions in synthetic forsterite crystals (Mg_2SiO_4) are recorded. Comparison of the observed shape of the spectral lines with the hyperfine structure calculated using crystal-field theory makes it possible to attribute the spectral lines to single centers and dimers for the first time.

A well-resolved hyperfine structure in optical spectra of holmium-doped synthetic forsterite Mg2SiO4 has been detected for the first time. Crystal-field calculations have been performed for single centers of impurity Ho3+ ions and dimers in forsterite Mg2SiO4.

Впервые обнаружена хорошо разрешенная сверхтонкая структура в оптических спектрах синтетического форстерита Mg2SiO4, легированного гольмием. Проведен расчет по теории кристаллического поля для одиночных центров примесных ионов Ho3+ и димеров в форстерите Mg2SiO4.

High-resolution low-temperature absorption spectra in the region of the 5I8 → 5I7, 6, 5, 4, 5F5 transitions in impurity Ho3+ ions in synthetic forsterite crystals (Mg2SiO4) are recorded. Comparison of the observed shape of the spectral lines with the hyperfine structure calculated using crystal-field theory makes it possible to attribute the spectral lines to single centers and dimers for the first time.