Faculty of Physics: Research Data

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Browsing Faculty of Physics: Research Data by Person "Kaib David A. S."

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  • Research Data
    Understanding the microscopic origin of the magnetic interactions in CoNb2O6
    2025-01-18
    Konieczna, Amanda Anna 
    Kaib David A. S.
    Winter, Steven M.
    Valentí, Roser
    Motivated by the on-going discussion on the nature of magnetism in the quantum Ising chain CoNb2O6, we present a first-principles-based analysis of its exchange interactions with additional modeling, addressing drawbacks of a purely density functional theory ansatz. This method allows us to extract and understand the origin of the magnetic couplings—including all symmetry-allowed terms - and resolve conflicting model descriptions in CoNb2O6. We find that the twisted Kitaev chain and transverse-field ferromagnetic Ising chain views are mutually compatible, although additional off- diagonal exchanges are required for a complete picture. We show that the dominant exchange interaction is a ligand-centered process—involving eg electrons -, rendered anisotropic by low- symmetry crystal fields in CoNb2O6, resulting in dominant Ising exchange. Smaller bond-dependent anisotropies are found to originate from d − d kinetic exchange processes involving t2g electrons. We demonstrate the validity of our low-energy model by comparing its predictions to measured THz and INS spectra.
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