Dynamical signatures of quantum spin liquids

A. Yuste, David Castells-Graells, Anna Sanpera

Nandini Trivedi

Guang-Yu Sun, Yan-Cheng Wang, Chen Fang +3 more

The nontriviality of quantum spin liquids (QSLs) typically manifests in the nonlocal observables that signify their existence; however, this fact actually casts a shadow on detecting QSLs with experimentally accessible probes. Here, we provide a solution by unbiasedly demonstrating a dynamical signature of anyonic excitations and symmetry fractionalization in QSLs. Employing large-scale quantum Monte Carlo simulation and stochastic analytic continuation, we investigate the extended XXZ model on the kagome lattice, and find out that, across the phase transitions from Z_{2} QSLs to different symmetry breaking phases, spin spectral functions can reveal the presence and condensation of emergent anyonic spinon and vison excitations, in particular, the translational symmetry fractionalization of the latter, which can be served as the dynamical signature of the seemingly ephemeral QSLs in spectroscopic techniques such as inelastic neutron or resonance (inelastic) x-ray scatterings.

Johannes Knolle

Minsu Park, Masafumi Udagawa, Eun-Gook Moon

A quantum spin liquid hosts massive quantum entanglement whose identification is one of the most significant problems in physics. Yet, its detection is known to be notoriously difficult because of featureless properties without a symmetry order parameter. Here, we demonstrate dynamic signatures of a quantum spin liquid state by investigating Kitaev's spin model on the hyper-honeycomb lattice, where a quantum spin liquid state is stabilized as a stable thermodynamic phase. The real-time dynamics of spin correlation function is obtained with the large-scale quantum Monte Carlo simulation. We find the onset of a characteristic oscillation in dynamic local spin correlation as entering the quantum spin liquid phase. Our results show that a quantum spin liquid may be characterized by a sharp growth of coherent spin dynamics of the system, which we name as a dynamic order. We further propose that a dynamic-order may naturally detect a featureless thermal phase transition, which has been reported in a class of strongly correlated materials.

Johannes Knolle, Dmitry L. Kovrizhin, J. T. Chalker +1 more

Quantum spin liquids are elusive states of matter, which have been predicted more than four decades ago but have not so far been conclusively sighted in nature. In this paper the authors study the so called `extended Kitaev model', which has a number of different quantum spin-liquid phases including one with non-Abelian excitations. They present a solution of a long standing problem for this model, namely, the problem of obtaining the dynamical response function. Using a rarely available exact calculation, they find that there are indeed clear signatures in the spin structure factor betraying the presence of spin-liquids and their fractionalized quasi-particles, including those with non-Abelian statistics.