SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Frustrated Magnets I
MA 33.5: Vortrag
Mittwoch, 29. März 2023, 16:15–16:30, HSZ 403
Disorder effects in the Kitaev-Heisenberg model — •Ayushi Singhania1, Jeroen van den Brink1,2, and Satoshi Nishimoto1,2 — 1Institute for Theoretical Solid State Physics, IFW Dresden, 01069 Dresden, Germany — 2Department of Physics, Technical University Dresden, 01069 Dresden, Germany
We study the interplay of disorder and Heisenberg interactions in Kitaev model on honeycomb lattice. The effect of disorder on the transition between Kitaev spin liquid and magnetic ordered states as well as the stability of magnetic ordering is investigated. Using Lanczos exact diagonalization we discuss the consequences of two types of disorder: random-coupling disorder & singular-coupling disorder. They exhibit qualitatively similar effects in the pure Kitaev-Heisenberg model without long-range interactions. The range of spin liquid phases is reduced and the transition to magnetic ordered phases becomes more crossover-like. Furthermore, the long-range zigzag and stripy orderings in the clean system are replaced by their three domains with different ordering direction. Especially in the crossover range the coexistence of magnetically ordered and Kitaev spin-liquid domains is possible. Surprisingly, in presence of long range interactions, the stability of magnetic ordered state is diminished by singular-coupling disorder, and accordingly, the range of spin-liquid regime is extended. This mechanism may be relevant to materials like α-RuCl3 and H3LiIr2O6 where the zigzag ground state is stabilized by weak long-range interactions. We also find that the flux gap closes at a critical disorder strength and vortices appears in the flux arrangement.