Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores Malkin, B. Z.; Lummen, T. T. A.; van Loosdrecht, P. H. M.; Dhalenne, G.; Zakirov, A. R. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractThe experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R 2 Ti 2 O 7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

Optical absorption spectra of the Yb 2 Ti 2 O 7 single crystals and luminescence spectra of the Y 2 Ti 2 O 7 :Yb (1%) polycrystalline samples were registered at temperatures 4.2-300 K. These spectra and earlier published data on magnetic properties of Yb 3+ ions and on the temperature dependence of the electric field gradient at Yb nuclei in Yb 2 Ti 2 O 7 were used to analyze the crystal-field parameters in rare-earth titanates with the pyrochlore structure. The self-consistent sets of crystal-field parameters for rare-earth ions in the 16d sites with the D 3d symmetry that describe satisfactory all known single-ion magnetic properties and low-energy excitations in R 2 Ti 2 O 7 crystals (R = Tb, Ho, Er, Tm, Yb) are presented.

We report high-resolution optical absorption spectra for NdFe 3 (BO 3 ) 4 trigonal single crystal which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering T N = 33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd 3+ 84 Kramers doublets. We perform crystalfield calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g-factors. In particular, the values g ⊥ = 2.385, g || = 1.376 were found for the Nd 3+ ground-state doublet. We obtain B loc =7.88 T and |J FN |= 0.48 K for the values of the local effective magnetic field at liquid helium temperatures at the Nd 3+ site and the Nd -Fe exchange integral, respectively, using the experimentally measured Nd 3+ ground-state splitting of 8.8 cm -1 . To check reliability of our set of crystal field parameters we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe 3+ ions J nn = -6.25 K (intrachain interactions) and J nnn = -1.92 K (inter-chain interactions) obtained from fitting agree well with the experimental data.

Abstract. Magnetic and magnetoelastic properties of terbium titanate pyrochlore in paramagnetic phase are simulated. The magnetic field and temperature dependences of magnetization and forced magnetostriction in Tb 2 Ti 2 O 7 single crystals and polycrystalline samples are calculated in the framework of exchange charge model of crystal field theory and a mean field approximation. The set of electron-deformation coupling constants has been determined. Variations of elastic constants with temperature and applied magnetic field are discussed. Additional strong softening of the crystal lattice at liquid helium temperatures in the magnetic field directed along the rhombic symmetry axis is predicted.

The article is devoted to the study of the attitude of Kazan residents to the prospect of not using a personal car as a means of transportation in the city. The aim of this study is to develop recommendations to popularize the idea of using public transport services of Kazan city residents on the basis of the analysis and its evaluation. To achieve the goal, the following main tasks were set and solved: a theoretical and empirical interpretation of the main concepts on the topic of the study; a comparative analysis of the volume of public costs from the use of a private car by residents of Kazan and their use of public transport services was carried out; the system of public transport in the city of Kazan was evaluated. The methodological tools of the study included a questionnaire survey and content analysis. As a result of the study, we found that at the moment there is indeed a problem within the city of Kazan, which consists in the impossibility of ensuring the universal transition of residents from the use of private cars to the consumption of public transport services, due to the lack of development of the relevant infrastructure.