EPR Identification of coupled Yb3+ ion pairs in optically bistable compound CsCdBr3 : Yb

Electron Paramagnetic Resonance (EPR) studies on ytterbium ions in weakly d oped CsCdBr3 are reported. Analysis of the characteristic features of the o bserved EPR spectra and their angular dependence shows that Yb3+ ions subst itute for Cd2+ ions in D-3d point site symmetry mainly to form weakly antif erromagnetically coupled symmetric pair complexes of the type Yb3+-V-Cd-Yb3 +, with interionic separation of around 5.9 Angstrom and J exchange couplin g value of -0.0016 cm(-1). Several weaker resonance lines are also observed which are assigned to single ion Yb3+ centers in perturbed sites of lower symmetry. (C) 2001 Elsevier Science B.V. All rights reserved.