Investigations on the g factors and local structure for the trigonal Ce3+ center in YAl3(BO3)4 crystal

The perturbation formulae of the EPR gyromagnetic factors g// and g⊥ for the lowest Kramers doublet of a 4f1 ion in trigonal symmetry are established. By using the above perturbation formulae, the anisotropic g factors and the local structure for the trigonal Ce3+ center in YAl3(BO3)4 crystal are theoretically studied. From the studies, this center is attributed to the impurity Ce3+ occupying the trigonal prism Y3+ site in YAl3(BO3)4. The Ce3+–O2− bond is found to undergo an angular variation Δθ(≈ 1.72°) related to the C3 axis. The calculated g factors based on the above impurity angular distortion display consistence with the measured results. The anisotropic g factors and the trigonal distortion of the Ce3+ center are analyzed with respect to the host Y3+ site in YAl3(BO3)4.

Coexistence of the magnetically ordered and Haldane states in (Y1-xNdx)2BaNiO5

The magnetic properties of (Y1-xNdx)2BaNiO5 with x = 0.01, 0.02, 0.03, 0.04, and 0.05 are investigated by means of specific heat, magnetic susceptibility, and spectroscopic measurements. We estimate a magnetic contribution of the neodymium subsystem into the magnetic susceptibility and specific heat using temperature dependencies of the splitting of the ground Kramers doublet of the Nd3+ ion obtained from spectroscopic experiments. We estimate also the contribution caused by nickel chain breaks and by ferrons. Different scenarios of low-temperature magnetic behavior are discussed.