Dynamic structure factor of the spin-12 XXZ chain in a transverse field

Benedikt Bruognolo, Andreas Weichselbaum, Jan von Delft, and Markus Garst
Phys. Rev. B 94, 085136 – Published 22 August 2016

Abstract

The spin-12 XXZ chain with easy-plane anisotropy in a transverse field describes well the thermodynamic properties of the material Cs2CoCl4 in a wide range of temperatures and fields including the region close to the spin-flop Ising quantum phase transition. For a comparison with prospective inelastic neutron scattering experiments on this compound, we present results of an extensive numerical study of its dynamic structure factor Sαβ(k,ω) using matrix-product-state (MPS) techniques. Close to criticality, the dynamic part of the correlator Sxx longitudinal to the applied field is incoherent and possesses a small total weight as the ground state is already close to saturation. The transverse correlator Szz, on the other hand, is dominated by a coherent single-particle excitation with additional spectral weight at higher energies that we tentatively attribute to a repulsively bound pair of particles. With increasing temperature, the latter quickly fades and spectral weight instead accumulates close to zero wave vector just above the single-particle energy. On a technical level, we compare the numerical efficiency of real-time evolution to an MPS-based Chebyshev expansion in the present context, finding that both methods yield results of similar quality at comparable numerical costs.

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  • Received 22 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.085136

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Benedikt Bruognolo1, Andreas Weichselbaum1, Jan von Delft1, and Markus Garst2,3

  • 1Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 München, Germany
  • 2Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77a, 50937 Köln, Germany
  • 3Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany

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Issue

Vol. 94, Iss. 8 — 15 August 2016

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