Topological spinon semimetals and gapless boundary states in three dimensions

Abstract

Recently there has been much effort in understanding topological phases of matter with gapless bulk excitations, which are characterized by topological invariants and protected intrinsic boundary states. Here we show that topological semimetals of Majorana fermions arise in exactly solvable Kitaev spin models on a series of three dimensional lattices. The ground states of these models are quantum spin liquids with gapless nodal spectra of bulk Majorana fermion excitations. It is shown that these phases are topologically stable as long as certain discrete symmetries are protected. The corresponding topological indices and the gapless boundary states are explicitly computed to support these results. In contrast to previous studies of non-interacting systems, the phases discussed in this work are novel examples of gapless topological phases in interacting spin systems.

arXiv comment5 pages and 2 figures. Supplemental material: 2 pages

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• Spin-Orbit Physics Giving Rise to Novel Phases in Correlated Systems: Iridates and Related Materials
• Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections
• Recent progress on correlated electron systems with strong spin-orbit coupling
• Long-range Coulomb interaction in nodal-ring semimetals
• Raman spectroscopic signature of fractionalized excitations in the harmonic-honeycomb iridates $\beta$- and $\gamma$-Li${}_2$IrO${}_3$
• Topological crystalline superconductivity and second-order topological superconductivity in nodal-loop materials
• Weyl spin liquids
• Theory of Raman response in three-dimensional Kitaev spin liquids: application to $\beta -$ and $\gamma -$Li${}_2$IrO${}_3$ compounds
• Topological surface superconductivity in doped Weyl loop materials
• Pressure-tuning of bond-directional exchange interactions and magnetic frustration in hyperhoneycomb iridate $\beta$-$\mathrm{L}{\mathrm{i}}_2\mathrm{Ir}{\mathrm{O}}_3$
• Weyl and Dirac Loop Superconductors
• Instabilities of Weyl-loop semi-metals
• Two iridates, two models, two approaches: a comparative study on magnetism in 3D honeycomb materials
• Dirac and Weyl Rings in Three Dimensional Cold Atom Optical Lattices
• Predominance of the Kitaev interaction in a three-dimensional honeycomb iridate: from ab-initio to spin model
• Topological magnetic excitations
• Revealing frustrated local moment model for pressurized hyperhoneycomb iridate: paving a way toward quantum spin liquid
• Interplay between short-range correlated disorder and Coulomb interaction in nodal-line semimetals
• Resonant Raman scattering theory for Kitaev models and their Majorana fermion boundary modes
• Magnonic Weyl states in Cu2OSeO3
• Edge magnetization and spin transport in an SU(2)-symmetric Kitaev spin liquid
• Further insights into the thermodynamics of the Kitaev honeycomb model
• Counter-rotating spiral order in three dimensional iridates: signature of hidden symmetry in Kitaev-$\Gamma$ model
• Vacancies in the Kitaev quantum spin liquids on the 3D hyper-honeycomb lattice
• Large Josephson current in Weyl nodal loop semimetals due to odd-frequency superconductivity
• Generic model for hyperkagome iridate in the local moment regime
• Raman scattering in correlated thin films as a probe of chargeless surface states
• Classification and properties of quantum spin liquids on the hyperhoneycomb lattice
• Resonant inelastic x-ray scattering spectra in the hyperhoneycomb iridate $\beta$-Li${}_2$IrO${}_3$: First principles calculations
• Weyl and nodal ring magnons in three-dimensional honeycomb lattices
• Entanglement in 3D Kitaev Spin Liquids
• Robust semi-Dirac points and unconventional topological phase transitions in doped superconducting Sr2IrO4 tunnel coupled to t2g electron systems
• Signatures of fractionalization in the optical phonons of hyperhoneycomb Kitaev magnet $\beta$-Li${}_2$IrO${}_3$
• Spin correlation and Majorana spectrum in chiral spin liquids in a decorated-honeycomb Kitaev model