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TT: Fachverband Tiefe Temperaturen

TT 86: Correlated Magnetism – Spin Liquids II

TT 86.7: Vortrag

Donnerstag, 12. März 2026, 16:30–16:45, CHE/0091

Phases and dynamics of the quadrupolar Kitaev model — •Partha Sarker and Urban Friedrich Peter Seifert — Institute for Theoretical Physics, University of Cologne, Zülpicher Straße 77, D-50937, Köln, Deutschland

The study of multipolar exchange interactions for local spin moments (S>1/2) has rapidly expanded in recent years. A crucial inquiry in this research landscape is whether the concept of quantum spin liquid can be generalized to multipolar liquids where multipolar moments fractionalize, giving rise to novel emergent phenomena. Recently, a model involving frustrated quadrupolar interactions between local S=1 moments has been numerically shown to host a deconfined phase with Z₂ topological order. We investigate various phases and dynamics of this model using a combination of mean-field and perturbative methods.

We first analytically demonstrate the existence of an extensively large set of ground states by probing the bare Hamiltonian with trivial deformations within the framework of generalized spin wave theory. The extensive degeneracy can be explained by the explicit construction of mean field ground states. These mean field ground states map to emergent electrostatics and can be divided into topological sectors in periodic boundary condition. Although perturbative analysis for anisotropic exchange coupling does not exhibit any evidence of deconfined excitations or topological ground state degeneracy, using parton analysis we can show that near the isotropic point the system hosts fractionalized gauge excitations. Finally, using parton mean field theory, we analyze the spectrum and various correlation functions.

Keywords: Kitaev Model; Multipolar liquids; Quantum Spin Liquids; Multipolar orders