Dirac and Chiral Quantum Spin Liquids on the Honeycomb Lattice in a Magnetic Field

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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Observation of plaquette fluctuations in the spin-1/2 honeycomb lattice

npj Quantum Materials ◽

10.1038/s41535-020-00287-1 ◽

2020 ◽

Vol 5 (1) ◽

Author(s):

Christian Wessler ◽

Bertrand Roessli ◽

Karl W. Krämer ◽

Bernard Delley ◽

Oliver Waldmann ◽

...

Keyword(s):

Quantum Critical Point ◽

Spin Correlation ◽

Quantum Spin ◽

Honeycomb Lattice ◽

Spin Liquids ◽

Spin Correlations ◽

Quantum Spin Liquids ◽

Dynamic Spin ◽

New Perspective ◽

The Continuum

AbstractQuantum spin liquids are materials that feature quantum entangled spin correlations and avoid magnetic long-range order at T = 0 K. Particularly interesting are two-dimensional honeycomb spin lattices where a plethora of exotic quantum spin liquids have been predicted. Here, we experimentally study an effective S = 1/2 Heisenberg honeycomb lattice with competing nearest and next-nearest-neighbour interactions. We demonstrate that YbBr3 avoids order down to at least T = 100 mK and features a dynamic spin–spin correlation function with broad continuum scattering typical of quantum spin liquids near a quantum critical point. The continuum in the spin spectrum is consistent with plaquette type fluctuations predicted by theory. Our study is the experimental demonstration that strong quantum fluctuations can exist on the honeycomb lattice even in the absence of Kitaev-type interactions, and opens a new perspective on quantum spin liquids.

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Multinode quantum spin liquids on the honeycomb lattice

Physical Review B ◽

10.1103/physrevb.102.144427 ◽

2020 ◽

Vol 102 (14) ◽

Author(s):

Jiucai Wang ◽

Qirong Zhao ◽

Xiaoqun Wang ◽

Zheng-Xin Liu

Keyword(s):

Quantum Spin ◽

Honeycomb Lattice ◽

Spin Liquids ◽

Quantum Spin Liquids

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Correlation holes and slow dynamics induced by fractional statistics in gapped quantum spin liquids

Nature Communications ◽

10.1038/s41467-021-21495-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Oliver Hart ◽

Yuan Wan ◽

Claudio Castelnovo

Keyword(s):

Transport Properties ◽

Realistic Model ◽

Feedback Mechanism ◽

Quantum Spin ◽

Spin Liquid ◽

Spin Liquids ◽

Slow Dynamics ◽

Temperature Dependent ◽

Quantum Spin Liquids ◽

Quantum Spin Liquid

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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