Crystal-field study for Yb3+ doped KY(WO4)2 crystal - Revisited based on superposition model

The optical spectra and electron paramagnetic resonance (EPR) parameters (gi and hyperfine structure constants Ai, i = x, y, z) for Yb3+:KY(WO4)2 crystal have been simultaneously explained by a crystal-field study based on superposition model (SPM). The deficiencies in a recent paper by Trabelsi et al. (2010) have been clarified and solved in the present work. The more reliable fitted phenomenological crystal-field parameters (CFPs) have been confirmed and monoclinic standardization of the obtained CFPs for Yb3+:KY(WO4)2 crystal is performed to ensure direct comparison with other rare earth ion doped potassium rare-earth double tungstates. By SPM calculations in this work, two individual EPR experiments with greatly different y-directional principal g factors for Yb3+:KY(WO4)2 crystal have been analyzed and possible reason for this large difference is also given. It indicates that magnetic dipolar and exchange interactions among different rare earth ions will play an important role in determining their magnetic properties in crystal under low temperature and more investigations should be carried out. The present procedures for SPM analysis can be applied to other crystal field environment with low site symmetry.