Kitaev spin-orbital bilayers and their moiré superlattices
Emilian M. Nica, Muhammad Akram, Aayush Vijayvargia, Roderich Moessner, Onur Erten
Abstract
Abstract We determine the phase diagram of a bilayer, Yao-Lee spin-orbital model with inter-layer interactions ( J ), for several stackings and moiré superlattices. For AA stacking, a gapped $${{\mathbb{Z}}}_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> quantum spin liquid phase emerges at a finite J c . We show that this phase survives in the well-controlled large- J limit, where an isotropic honeycomb toric code emerges. For moiré superlattices, a finite- q inter-layer hybridization is stabilized. This connects inequivalent Dirac points, effectively ‘untwisting’ the system. Our study thus provides insight into the spin-liquid phases of bilayer spin-orbital Kitaev materials.