Dresden 2026 – scientific programme
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MA: Fachverband Magnetismus
MA 19: Frustrated Magnets I (joint session MA/TT)
MA 19.5: Talk
Tuesday, March 10, 2026, 10:30–10:45, POT/0361
Evidence for a Near-Ideal Jeff = 1/2 Ground State in Triangular-Lattice Na2BaCo(PO4)2 — •Miguel M. F. Carvalho1,2, Sheng H. Chen1, Yu C. Ku3,4, Anagha Jose5, Ryan Morrow5, Chang Y. Kuo3,4, Chun F. Chang1, Zhiwei Hu1, Maurits W. Haverkort6, and Liu H. Tjeng1 — 1Max Planck Institute for Chemical Physics of Solids,Dresden — 2Institute of Physics II, University of Cologne — 3Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan — 4National Synchrotron Radiation Research Center, Hsinchu, Taiwan — 5Institut fuer Festkoerperphysik, Leibniz IFW, Dresden — 6Institute for theoretical physics, Heidelberg University
We investigated the local Co 3d electronic structure of Na2BaCo(PO4)2 using polarization-dependent X-ray absorption spectroscopy (XAS) together with full multiplet cluster calculations. To obtain reliable spectra from this strongly insulating material, we employed the line-fitting inverse partial fluorescence yield (IPFY) method. Our combined experimental and theoretical analysis shows that the CoO6 octahedra exhibit only a very small effective trigonal distortion of about 11 meV, placing the system close to the ideal conditions for a Jeff = 1/2 ground state. Using our cluster model, we are also able to simulate the magnetic susceptibility along different crystallographic directions, . Overall, these results establish Na2BaCo(PO4)2 as a promising platform for investigating exotic magnetic behavior linked to Jeff = 1/2 states on triangular lattices.
Keywords: Triangular lattice; X-ray Absorption Spectroscopy; Electronic structure; Strongly correlated systems