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MA: Fachverband Magnetismus

MA 3: Complex Magnetic Oxides

MA 3.10: Vortrag

Montag, 9. März 2026, 12:00–12:15, POT/0112

resonant inelastic x-ray scattering spectra of the dynamic jahn-teller Cu²⁺ center in CuAl₂O₄ — •Takumi Gengo¹, Kenta Touge², Ara Go³, and Naoya Iwahara¹ — ¹Graduate School of Engineering, Chiba University, Chiba, Japan — ²Department of Materials Science, Faculty of Engineering, Chiba University, Chiba, Japan — ³Department of Physics, Chonnam National University, Gwangju, South Korea

Cu spinel compounds such as CuAl₂O₄ and CuGa₂O₄ attract attention as spin-orbit entangled magnets. The density mean-field theory calculations show that the spin-orbit coupling on the Cu site suppresses the Jahn-Teller deformation in the ground state, which is consistent with the x-ray diffraction data. On the contrary, recent resonant inelastic x-ray scattering (RIXS) measurement of CuAl₂O₄ suggests the possibility that the Jahn-Teller deformation develops. Such a contradictory situation could occur due to the development of the dynamic Jahn-Teller effect .

This study aims to theoretically elucidate the nature of quantum states on Cu sites induced by the competition between spin-orbit and electron-phonon (vibronic) couplings. We successfully reproduced the Cu L₂- and L₃-edge RIXS spectra based on our model with the quantum mechanical treatment of the lattice degrees of freedom (i.e., dynamic Jahn-Teller effect), which is consistent with the structural data. This study supports the former theoretical prediction that CuAl₂O₄ is a 3d spin-orbit coupled magnet.

Keywords: Cu; Jahn-Teller; Spinel; RIXS