2018/07/31 by Jad C. Halimeh, Rajiv R. P. Singh · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.mtrl-sci #quant-ph
paper · pdf · doi:10.1103/physrevb.99.155151
published as Phys. Rev. B 99, 155151 (2019) · Accepted version, journal article, 17 pages, 12 figures, including 4 appendices
arxiv created 2019/04/17 · arxiv updated 2019/05/01
Using Schwinger-boson mean-field theory, we calculate the dynamic spin structure factor at low temperatures 0<T≪ J for the spin-1/2 antiferromagnetic Heisenberg kagome model, within the gapped ℤ2 spin liquid phase Ansatz. We find that the spectral gap rapidly fills with temperature, with robust low-energy spectral weight developing by a temperature of Δ/3, where the spin gap is 2Δ (i.e., Δ is the spinon gap), before any appreciable rise in spinon density or change in zero-temperature mean-field parameters. This is due to deconfinement of spinons which leads to terms suppressed only by exp(-Δ/T). At still higher temperatures, the spinon density increases rapidly leading to a breakdown of the Schwinger-boson mean-field approach. We suggest that if the impurity-free spectral functions can be obtained through neutron scattering experiments on kagome herbertsmithites, temperature dependence of the subgap weight can provide distinct signatures of a ℤ2 quantum spin liquid.