Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 53: Frustrated Magnets - Strong Spin-Orbit Coupling (joint session TT/MA)

TT 53.11: Talk

Thursday, April 4, 2019, 12:15–12:30, Theater

Field-induced phases in extended Kitaev models: Insights from hidden symmetries and relevance for real materials — •David Kaib, Stephen Winter, and Roser Valenti — Institut für Theoretische Physik, Goethe-Universität Frankfurt

At zero magnetic field, Kitaev’s honeycomb model hosts a Z₂ spin liquid with itinerant Majorana fermions. We study a field-induced intermediate phase (IP) in the antiferromagnetic (AFM) Kitaev model, which has been discussed in terms of a gapless U(1) spin liquid [1-3].

In order to characterize the IP, we consider various dynamical correlations, calculated via exact diagonalization (ED). By analyzing hidden symmetries of the model, we discuss which general nonuniform fields retain the IP, and introduce nonuniform fields that relate the field-response of the AFM model to the FM model. Within ED resolution, we find that the IP could represent a line of critical points within the parameter space of such fields.

At last, we turn to models with extended interactions, in order to relate to real materials. Since the candidate materials are thought to realize ferromagnetic (FM) coupling, we identify an extended model with FM Kitaev coupling, that is dual to the pure AFM Kitaev model, and study its vicinity to Hamiltonians of real materials.
C. Hickey et al., arXiv:1805.05953
H.-C. Jiang et al., arXiv:1809.08247
L. Zou et al., arXiv:1809.09091