Dynamical Structure Factor of the Three-Dimensional Quantum Spin Liquid Candidate ${\mathrm{NaCaNi}}_{2}{\mathrm{F}}_{7}$

Dynamical Structure Factor of the Three-Dimensional Quantum Spin Liquid Candidate ${NaCaNi}_{2} F_{7}$

Shu Zhang, Hitesh J. Changlani, Kemp W. Plumb, Oleg Tchernyshyov, and Roderich Moessner

Phys. Rev. Lett. 122, 167203 – Published 26 April 2019

Abstract

We study the dynamical structure factor of the spin-1 pyrochlore material ${NaCaNi}_{2} F_{7}$ , which is well described by a weakly perturbed nearest-neighbour Heisenberg Hamiltonian, Our three approaches—molecular dynamics simulations, stochastic dynamical theory, and linear spin wave theory—reproduce remarkably well the momentum dependence of the experimental inelastic neutron scattering intensity as well as its energy dependence with the exception of the lowest energies. We discuss two surprising aspects and their implications for quantum spin liquids in general: the complete lack of sharp quasiparticle excitations in momentum space and the success of the linear spin wave theory in a regime where it would be expected to fail for several reasons.

Received 30 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.167203

Physics Subject Headings (PhySH)

Quantum spin liquid Spin dynamics

Heisenberg model Neutron scattering

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Shu Zhang^1,2, Hitesh J. Changlani^3,4,1,2, Kemp W. Plumb⁵, Oleg Tchernyshyov^1,2, and Roderich Moessner⁶

¹Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
²Institute for Quantum Matter, Johns Hopkins University, Baltimore, Maryland 21218, USA
³Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
⁴National High Magnetic Field Laboratory, Tallahassee, Florida 32304, USA
⁵Department of Physics, Brown University, Providence, Rhode Island 02912, USA
⁶Max-Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany