The Kitaev spin model on a honeycomb lattice with competing bond-dependent interactions describes a quantum spin liquid with topological order and fractionalized excitations. Such models can be realized in Mott insulators with strong spin-orbit coupling. The main question we ask is: what is the manifestation of bond-dependent frustration in the opposite weakly correlated metallic limit? We show that when inter-orbital hopping dominates over intra-orbital hopping, it is possible to get extremely flat bands without fine-tuning. Going beyond quantum Hall effect and twisted bilayer graphene, we provide an alternative mechanism and a richer materials platform for achieving flat bands poised at the brink of instabilities toward novel correlated and fractionalized metallic phases.

References: 

[1] Orbital Frustration and Emergent Flat Bands, Wenjuan Zhang, Zachariah Addison, Nandini Trivedi, arXiv:2102.06302.

[2] Magnetic field induced intermediate quantum spin-liquid with a spinon Fermi surface, Niravkumar D. Patel, Nandini Trivedi, Proc. Nat. Acad.Sc. 116 12199 (2019).

[3] Field-orientation-dependent spin dynamics of the Kitaev honeycomb model, David C. Ronquillo, Adu Vengal, Nandini Trivedi, Phys. Rev. B 99 140413(2019).