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; Roderich Moessner

doi:10.1103/PhysRevLett.122.167203

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

Phys Rev Lett. 2019 Apr 26;122(16):167203. doi: 10.1103/PhysRevLett.122.167203.

Authors

Shu Zhang^{1

2}, Hitesh J Changlani^{1

2

3

4}, Kemp W Plumb⁵, Oleg Tchernyshyov^{1

2}, Roderich Moessner⁶

Affiliations

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

PMID: 31075014
DOI: 10.1103/PhysRevLett.122.167203

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.