Reanalysis of crystal field parameter datasets for rare-earth ions at low symmetry sites: Nd3+ in NdGaO3 and Pr3+ in PrGaO3

Noether's theorem and low symmetry aspects concerning the crystal (ligand) field Hamiltonians and spin Hamiltonians

“…Spectroscopic properties of the transition ions, especially iron-group ions and lanthanides, at low symmetry sites in crystals play important role for various technologically important materials (for references, see [1][2][3][4][5]). The trivalent rare-earth (RE) 4f N ions have been most extensively studied due to applications in laser host and optoelectronic materials.…”

“…The experimental techniques employed to investigate the CF/LF effects, majority of which are 'non-directional' techniques -unlike those used in the EMR (electron magnetic resonance) studies [6,7], were discussed in [3]. During our recent CF/LF studies of transition ions in crystals [1][2][3][4][5] we have encountered several intricate low symmetry aspects. The motivation to clarify these aspects has prompted us to embark on a comprehensive project aimed at increasing the compatibility and reliability of the crystal field parameter (CFP) datasets.…”

“…This review presents a concise summary of the major findings arising from our studies concerning the intricate low symmetry properties of CF/LF Hamiltonians and spin Hamiltonians (SHs). To facilitate broad understanding, a bird's-eye view of these studies is given in Section 2, where the recent results [1][2][3][4][5] are briefly outlined, whereas our earlier pertinent studies [8][9][10][11][12] are put in perspective. To provide theoretical background for the underlying considerations, the pertinent basic concepts and notations are overviewed in Section 3.…”

“…The results presented in Sections 6 and 7 enable a new look at the properties of CF/LF Hamiltonians and SHs for CRS cases and consideration of practical applications in Section 8. Since this review is based on our published papers, especially the recent ones [1][2][3][4][5], instead of a full list of references and as a space saving measure, we provide here only pointers to the authors' papers. Hence, these references shall be considered as sources of specific references to pertinent literature and not as mere self-citations.…”

“…Hence, these references shall be considered as sources of specific references to pertinent literature and not as mere self-citations. For completeness, the most recent relevant papers not cited in [1][2][3][4][5] are briefly commented on in Conclusions (Section 9). …”