Development of the formulation of the crystalline-electric-field theory in quasicrystal

The lack of the microscopic theory for the crystalline electric field (CEF) in the rare-earth-based quasicrystal (QC) has prevented us from understanding the electronic state. We have succeeded in developing the general formulation of the CEF theory on the basis of the point charge model.

On the basis of the point charge model, we formulate the CEF Hamiltonian HCEF in the rare-earth based QC and approximant crystal (AC) with ligand ions located at pseudo 5-fold configurations by using the operator equivalent method. By setting the total angular momentum J=7/2, the CEF in the quantum critical QC Au51Al34Yb15 and the 1/1 AC Au51Al35Yb14 is analyzed with consideration for the effect of Al/Au mixed sites. We find that the ratio of the valences of ligand ions α=ZAl/ZAu plays an important role in characterizing the CEF ground state. As x decreases from α=3, the 4f wave function of the CEF ground state with the flat shape lying in the mirror plane is deformed around α≈0.8 to the flat shape perpendicular to the pseudo 5-fold axis at α=0. The formulated HCEF by J is generally applicable to rare-earth-based QCs and ACs, which is useful to analyze the CEF.


[1] S. Watanabe and M. Kawamoto: J. Phys. Soc. Jpn. 90 (2021) 063701.



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Last updated: Sept 9 2023