Gotfryd, Dorota; Paerschke, EkaterinaIST Austria ; Chaloupka, Jiri; Oles, Andrzej M.; Wohlfeld, Krzysztof
The concept of the entanglement between spin and orbital degrees of freedom plays a crucial role in our understanding of various phases and exotic ground states in a broad class of materials, including orbitally ordered materials and spin liquids. We investigate how the spin-orbital entanglement in a Mott insulator depends on the value of the spin-orbit coupling of the relativistic origin. To this end, we numerically diagonalize a one-dimensional spin-orbital model with Kugel-Khomskii exchange interactions between spins and orbitals on different sites supplemented by the on-site spin-orbit coupling. In the regime of small spin-orbit coupling with regard to the spin-orbital exchange, the ground state to a large extent resembles the one obtained in the limit of vanishing spin-orbit coupling. On the other hand, for large spin-orbit coupling the ground state can, depending on the model parameters, either still show negligible spin-orbital entanglement or evolve to a highly spin-orbitally-entangled phase with completely distinct properties that are described by an effective XXZ model. The presented results suggest that (i) the spin-orbital entanglement may be induced by large on-site spin-orbit coupling, as found in the 5d transition metal oxides, such as the iridates; (ii) for Mott insulators with weak spin-orbit coupling of Ising type, such as, e.g., the alkali hyperoxides, the effects of the spin-orbit coupling on the ground state can, in the first order of perturbation theory, be neglected.
Physical Review Research
Gotfryd D, Paerschke E, Chaloupka J, Oles AM, Wohlfeld K. How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator. Physical Review Research. 2020;2(1). doi:10.1103/PhysRevResearch.2.013353
Gotfryd, D., Paerschke, E., Chaloupka, J., Oles, A. M., & Wohlfeld, K. (2020). How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator. Physical Review Research, 2(1). https://doi.org/10.1103/PhysRevResearch.2.013353
Gotfryd, Dorota, Ekaterina Paerschke, Jiri Chaloupka, Andrzej M. Oles, and Krzysztof Wohlfeld. “How Spin-Orbital Entanglement Depends on the Spin-Orbit Coupling in a Mott Insulator.” Physical Review Research 2, no. 1 (2020). https://doi.org/10.1103/PhysRevResearch.2.013353.
D. Gotfryd, E. Paerschke, J. Chaloupka, A. M. Oles, and K. Wohlfeld, “How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator,” Physical Review Research, vol. 2, no. 1, 2020.
Gotfryd D, Paerschke E, Chaloupka J, Oles AM, Wohlfeld K. 2020. How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator. Physical Review Research. 2(1).
Gotfryd, Dorota, et al. “How Spin-Orbital Entanglement Depends on the Spin-Orbit Coupling in a Mott Insulator.” Physical Review Research, vol. 2, no. 1, 013353, American Physical Society, 2020, doi:10.1103/PhysRevResearch.2.013353.
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