Fig. 6: Theoretical exchange parameters.
From: Proximate ferromagnetic state in the Kitaev model material α-RuCl3
Exchange parameters K (red), J (black), Γ (blue), and \({{{\Gamma }}}^{\prime}\) (gray) as a function of δ = 2Δ/λ, calculated using 10Dq = 2.4 eV, JH = 0.34 eV, and the pd charge-transfer gap Δpd = 5.5 eV as obtained from the RIXS data (Fig. 2). We use representative values of the Coulomb interaction U = 2.5 eV for the Ru-d orbitals, Up = 1.5 eV and Hund’s coupling Jp = 0.7 eV for the Cl-p orbitals, a ratio of tpdσ/tpdπ = 2 between the pd charge-transfer integrals in the σ and π channels, and a direct t2g hopping \(t^{\prime} =0.4t\). The exchange constants are given in units of t2/U. The vertical gray line indicates δ ~ − 0.7 appropriate for RuCl3.
