How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator Gotfryd, Dorota Paerschke, Ekaterina ; https://orcid.org/0000-0003-0853-8182 Chaloupka, Jiri Oles, Andrzej M. Wohlfeld, Krzysztof ddc:530 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. American Physical Society 2020 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/7594 https://research-explorer.ista.ac.at/download/7594/7610 Gotfryd D, Paerschke E, Chaloupka J, Oles AM, Wohlfeld K. How spin-orbital entanglement depends on the spin-orbit coupling in a Mott insulator. <i>Physical Review Research</i>. 2020;2(1). doi:<a href="https://doi.org/10.1103/PhysRevResearch.2.013353">10.1103/PhysRevResearch.2.013353</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevResearch.2.013353 info:eu-repo/semantics/openAccess