EPR spectra and magnetization of XY-type rare-earth ions in pyrochlores Y${}_2$Ti${}_2$O${}_7$:RE${}^{3+}$ (RE=Yb, Er)

Abstract

The results of studies of Y${}_2$Ti${}_2$O${}_7$ single crystals doped with Er${}^{3+}$ and Yb${}^{3+}$ ions by means of electron paramagnetic resonance (EPR) and dc-magnetometry are reported. EPR signals of the trigonal centers with the characteristic hyperfine structure of Er${}^{3+}$ or Yb${}^{3+}$ ions were observed. Field dependences of magnetization of single crystals for magnetic fields directed along the crystallographic axes and temperature dependences of magnetic susceptibilities were measured. Spin Hamiltonian parameters ($g$-factors and parameters of the hyperfine interaction) for Er${}^{3+}$ and Yb${}^{3+}$ ions were obtained from analysis of experimental data. The registered EPR spectra and magnetization curves were successfully reproduced by simulations in framework of the crystal-field approach, in particular, with an account for hybridization of ground 4f${}^{13}$ configuration of Yb${}^{3+}$ ions with the charge transfer states.

12 pages, 4 figures, 2 tables