Spectroscopic and Crystal Field Investigation of Kramers-Ions: Nd 3+:YAB—a Case Study of the Crystal Field Structure of the 4I 9/2 Ground State

Abstract

Single crystals of yttrium aluminium borate, YAl 3(BO 3) 4, (referred to as YAB) doped with 20 and 40 mol% of Nd 3+ were grown using a flux growth method. Inconsistencies in regard to the reported ground state splitting of the doped material are pointed out. A consistent splitting and assignment of the 4 I 9/2 ground state levels of the Kramers-ion Nd 3+ was obtained by a combination of both, temperature-dependent 4 I 9/2→ 2 P 9/2 polarized absorption spectroscopy and room temperature 4 F 9/2→ 4 I 9/2 luminescence spectroscopy. The group theoretical implications of the crystal field analysis are considered and discussed.