The Spectral and Magnetic Properties of Er3+ and Yb3+ Ions in Y2Ti2O7 Crystals with a Pyrochlore Structure

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Cubic Y₂Ti₂O₇ single crystals doped with Er³⁺ or Yb³⁺ ions have been studied by the methods of electron spin resonance (ESR) and selective laser spectroscopy. ESR spectra exhibit signals from rare-earth ions that substitute for yttrium ions in sites with local trigonal symmetry. The g tensor components are determined. The results of optical investigations indicate that impurity centers of several types are formed; the sublevel energies of the ground and excited multiplets of these centers are found. Among the great variety of detected optical centers, the centers that dominate in the formation of ESR spectra are discriminated. An analysis of the experimental data using the exchange-charge model have made it possible to determine the sets of parameters of the crystal field for Er³⁺ and Yb³⁺ ions substituting Y³⁺ ions in regular crystallographic sites in pyrochlore Y₂Ti₂O₇.