Research: Ordered state in the Kitaev-Heisenberg model: from 1D to 2D

Quantum spin liquids are nowadays of great interest in the field of condensed matter. In particular, the Kitaev spin liquid is relevant as it presents nontrivial topological phases and Majorana modes. Possible Kitaev material candidates are better described by an extension of the original model, leading to the so called Kitaev-Heisenberg model. Those materials show magnetically ordered states at low temperature. However, recent experimental results suggest the Kitaev spin liquid is derived from a melting of the magnetic ordering by field or pressure. To theoretically study this mechanism, we need to understand the characteristics of the magnetically ordered state of the 2D Kitaev-Heisenberg model. Though the 2D honeycomb case has been widely studied, the Kitaev-Heisenberg chain has so far attracted little attention.

Using the density matrix renormalization group technique, we study the full phase diagram of the Kitaev-Heisenberg chain and show how the 2D honeycomb ordered states can be interpreted in term of coupled chains. Moreover, we suggest possible candidate materials for this model and present its elementary excitations.

By drawing a connection between 1D chains and the 2D honeycomb, we offer a new point of view on the Kitaev-Heisenberg model.

C. E. Agrapidis, J. van den Brink, S. Nishimoto,
Ordered states in the Kitaev-Heisenberg model: From 1D chains to 2D honeycomb,
Sci. Rep. 8, 1815 (2018) (arXiv)