Physical Review Research (Dec 2021)

Solitonic excitations in the Ising anisotropic chain BaCo_{2}V_{2}O_{8} under large transverse magnetic field

  • Quentin Faure,
  • Shintaro Takayoshi,
  • Béatrice Grenier,
  • Sylvain Petit,
  • Stéphane Raymond,
  • Martin Boehm,
  • Pascal Lejay,
  • Thierry Giamarchi,
  • Virginie Simonet

DOI
https://doi.org/10.1103/PhysRevResearch.3.043227
Journal volume & issue
Vol. 3, no. 4
p. 043227

Abstract

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We study the dynamics of the quasi-one-dimensional Ising-Heisenberg antiferromagnet BaCo_{2}V_{2}O_{8} under a transverse magnetic field. Combining inelastic neutron scattering experiments and theoretical analyses by field theories and numerical simulations, we mainly elucidate the structure of the spin excitation spectrum in the high-field phase, appearing above the quantum phase transition point μ_{0}H_{c}≈10T. We find that it is characterized by collective solitonic excitations superimposed on a continuum. These solitons are strongly bound in pairs due to the effective staggered field induced by the nondiagonal g tensor of the compound and are topologically different from the fractionalized spinons in the weak-field region. The dynamical susceptibility numerically calculated with the infinite time-evolving block decimation method shows an excellent agreement with the measured spectra, which enables us to identify the dispersion branches with elementary excitations. The lowest-energy dispersion has an incommensurate nature and has a local minimum at an irrational wave number due to the applied transverse field.