Microscopic origin of isotropic non-Heisenberg behavior in highly correlated systems

Abstract

We have reanalyzed the microscopic origin of the isotropic deviations that are observed from the energy spacings predicted by the HDVV Hamiltonian. Usually, a biquadratic spin operator is added to the HDVV Hamiltonian to account for such deviations. It is shown here that this operator cannot describe the effect of the excited atomic non-Hund states which brought the most important contribution to the deviations. For systems containing more than two magnetic centers, non-Hund states cause additional interactions that are of the same order of magnitude as the biquadratic exchange and should have significant effects on the macroscopic properties of extended systems.

arXiv comment4 pages, 3 figures

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• Spin nematic correlations in bilinear-biquadratic S=1 spin chains
• Spin nematics in the bilinear-biquadratic S=1 spin chain
• Possible ferro-spin nematic order in NiGa2S4
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• Theory of inelastic light scattering in spin-1 systems: resonant regimes and detection of quadrupolar order
• $ab$-$initio$ Approaches for Low-Energy Spin Hamiltonians
• Control of Magnetic and Topological Orders with a DC Electric Field
• Phase diagram of the spin-1 Heisenberg model with three-site interactions on the square lattice
• Thermodynamic observables of Mn12-acetate calculated for the full spin-Hamiltonian
• Ground-state entanglement of spin-1 bosons undergoing superexchange interactions in optical superlattices
• Emergence of Spinmerism for Molecular Spin-Qubits Generation
• Is Herbertsmithite far from an ideal antiferromagnet? Ab-initio answer including in-plane Dzyaloshinskii-Moriya interactions and coupling with extra-plane impurities
• Phenomenological theory of magnetic 90${}^{\circ }$ helical state
• Heisenberg spin chains with additional isotropic three-site exchange interactions
• Effective Hamiltonians from Spin Adapted Configuration Interaction
• Spin-pure Stochastic-CASSCF via GUGA-FCIQMC applied to Iron Sulfur Clusters