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arXiv · 1611.03436

Kitaev-Heisenberg model in a magnetic field: order-by-disorder and commensurate-incommensurate transitions

Gia-Wei Chern·Yuriy Sizyuk·Craig Price·Natalia B. Perkins
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Abstract

We present a theoretical study of field-induced magnetic phases in the honeycomb Kitaev-Heisenberg model, which is believed to describe the essential physics of Mott insulators with strong spin-orbit coupling such as $A_2$IrO$_3$ and $\alpha$-RuCl$_3$. We obtain a finite temperature phase diagram based on extensive Monte Carlo simulations and analytical calculations. We show that, while Zeeman coupling favors a symmetric non-coplanar magnetic order, thermal fluctuations enhances the stability of a collinear zigzag phase that breaks the rotational symmetry of the lattice. Our large-scale simulations also uncover intriguing commensurate-incommensurate transitions and multiple-$\mathbf Q$ incommensurate phases at high field. Experimental implications are also discussed.

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Gia-Wei Chern, Yuriy Sizyuk, Craig Price, Natalia B. Perkins. 2016-11-10. Kitaev-Heisenberg model in a magnetic field: order-by-disorder and commensurate-incommensurate transitions. https://doi.org/10.1103/physrevb.95.144427

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