• Open Access

Disorder effects in the Kitaev-Heisenberg model

Ayushi Singhania, Jeroen van den Brink, and Satoshi Nishimoto
Phys. Rev. Research 5, 023009 – Published 5 April 2023

Abstract

We study the interplay of disorder and Heisenberg interactions in the Kitaev model on a 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: (i) random-coupling disorder and (ii) 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 crossoverlike. 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. With increasing the disorder strength the area of domains becomes smaller and the system goes into a spin-glass state. However, the disorder effect is different in magnetically ordered phases caused by long-range interactions. The stability of such magnetic ordering is diminished by singular-coupling disorder and, accordingly, the range of the spin-liquid regime is extended. This mechanism may be relevant to materials like αRuCl3 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. Interestingly, the vortices tend to form kinds of commensurate ordering.

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  • Received 10 November 2022
  • Revised 26 February 2023
  • Accepted 1 March 2023

DOI:https://doi.org/10.1103/PhysRevResearch.5.023009

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

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

  • *Corresponding author: a.singhania@ifw-dresden.de

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Vol. 5, Iss. 2 — April - June 2023

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