Journal article
Phase diagram and quantum order by disorder in the kitaev K1 - K2 honeycomb magnet
I Rousochatzakis, J Reuther, R Thomale, S Rachel, NB Perkins
Physical Review X | AMER PHYSICAL SOC | Published : 2015
Open access
Abstract
We show that the topological Kitaev spin liquid on the honeycomb lattice is extremely fragile against the second-neighbor Kitaev coupling K2, which has recently been shown to be the dominant perturbation away from the nearest-neighbor model in iridate Na2IrO3, and may also play a role in α-RuCl3 and Li2IrO3. This coupling naturally explains the zigzag ordering (without introducing unrealistically large longer-range Heisenberg exchange terms) and the special entanglement between real and spin space observed recently in Na2IrO3. Moreover, the minimal K1 - K2 model that we present here holds the unique property that the classical and quantum phase diagrams and their respective order-by-disorder..
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Awarded by European Commission
Funding Acknowledgements
We acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota and the Max Planck Institute for the Physics of Complex Systems, Dresden, where a large part of the numerical computations took place. We are also grateful to R. Moessner, C. Price, O. Starykh, G. Jackeli, Y. Sizyuk, P. Mellado, and M. Schulz for stimulating discussions. I. R. and N. B. P. acknowledge support from NSF Grant No. DMR-1511768. J. R. was supported by the Freie Universitat Berlin within the Excellence Initiative of the German Research Foundation. R. T. was supported by the European Research Council through ERC-StG-336012 and by DFG-SFB 1170. S. R. was supported by DFG-SFB 1143, DFG-SPP 1666, and by the Helmholtz association through VI-521. S. R., R. T. and N. B. P. acknowledge the hospitality of the KITP during the program "New Phases and Emergent Phenomena in Correlated Materials with Strong Spin-Orbit Coupling" and partial support by the National Science Foundation under Grant No. NSF PHY11-25915.