Randomness-induced quantum spin liquid on honeycomb lattice

AbstractRealistic model Hamiltonians for quantum spin liquids frequently exhibit a large separation of energy scales between their elementary excitations. At intermediate, experimentally relevant temperatures, some excitations are sparse and hop coherently, whereas others are thermally incoherent and dense. Here, we study the interplay of two such species of quasiparticle, dubbed spinons and visons, which are subject to nontrivial mutual statistics – one of the hallmarks of quantum spin liquid behaviour. Our results for $${{\mathbb{Z}}}_{2}$$ Z 2 quantum spin liquids show an intriguing feedback mechanism, akin to the Nagaoka effect, whereby spinons become localised on temperature-dependent patches of expelled visons. This phenomenon has important consequences for the thermodynamic and transport properties of the system, as well as for its response to quenches in temperature. We argue that these effects can be measured in experiments and may provide viable avenues for obtaining signatures of quantum spin liquid behaviour.

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Gapless Quantum Spin Liquid in the Triangular System Sr3CuSb2O9

Physical Review Letters ◽

10.1103/physrevlett.125.267202 ◽

2020 ◽

Vol 125 (26) ◽

Author(s):

S. Kundu ◽

Aga Shahee ◽

Atasi Chakraborty ◽

K. M. Ranjith ◽

B. Koo ◽

...

Keyword(s):

Quantum Spin ◽

Spin Liquid ◽

Triangular System ◽

Quantum Spin Liquid

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Giant phonon anomalies in the proximate Kitaev quantum spin liquid α-RuCl3

Nature Communications ◽

10.1038/s41467-021-23826-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Haoxiang Li ◽

T. T. Zhang ◽

A. Said ◽

G. Fabbris ◽

D. G. Mazzone ◽

...

Keyword(s):

Acoustic Phonon ◽

Energy Scale ◽

Quantum Spin ◽

Majorana Fermion ◽

Spin Liquid ◽

Optical Phonons ◽

Large Intensity ◽

Topological Quantum ◽

Topological State ◽

Quantum Spin Liquid

AbstractThe Kitaev quantum spin liquid epitomizes an entangled topological state, for which two flavors of fractionalized low-energy excitations are predicted: the itinerant Majorana fermion and the Z2 gauge flux. It was proposed recently that fingerprints of fractional excitations are encoded in the phonon spectra of Kitaev quantum spin liquids through a novel fractional-excitation-phonon coupling. Here, we detect anomalous phonon effects in α-RuCl3 using inelastic X-ray scattering with meV resolution. At high temperature, we discover interlaced optical phonons intercepting a transverse acoustic phonon between 3 and 7 meV. Upon decreasing temperature, the optical phonons display a large intensity enhancement near the Kitaev energy, JK~8 meV, that coincides with a giant acoustic phonon softening near the Z2 gauge flux energy scale. These phonon anomalies signify the coupling of phonon and Kitaev magnetic excitations in α-RuCl3 and demonstrates a proof-of-principle method to detect anomalous excitations in topological quantum materials.

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Quantum loop states in spin-orbital models on the honeycomb lattice

Nature Communications ◽

10.1038/s41467-021-23033-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Lucile Savary

Keyword(s):

Realistic Model ◽

Quantum Spin ◽

Honeycomb Lattice ◽

Spin Liquids ◽

Spin Orbital ◽

Experimental Realization ◽

Quantum Phases ◽

Quantum Spin Liquids ◽

Quantum Spin Liquid ◽

Symmetry Protected

AbstractThe search for truly quantum phases of matter is a center piece of modern research in condensed matter physics. Quantum spin liquids, which host large amounts of entanglement—an entirely quantum feature where one part of a system cannot be measured without modifying the rest—are exemplars of such phases. Here, we devise a realistic model which relies upon the well-known Haldane chain phase, i.e. the phase of spin-1 chains which host fractional excitations at their ends, akin to the hallmark excitations of quantum spin liquids. We tune our model to exactly soluble points, and find that the ground state realizes Haldane chains whose physical supports fluctuate, realizing both quantum spin liquid like and symmetry-protected topological phases. Crucially, this model is expected to describe actual materials, and we provide a detailed set of material-specific constraints which may be readily used for an experimental realization.

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