Confinement of Fractional Excitations in a Triangular Lattice Antiferromagnet

Phys Rev Lett. 2023 Jun 23;130(25):256702. doi: 10.1103/PhysRevLett.130.256702.

Abstract

High-resolution neutron and THz spectroscopies are used to study the magnetic excitation spectrum of Cs_{2}CoBr_{4}, a distorted-triangular-lattice antiferromagnet with nearly XY-type anisotropy. What was previously thought of as a broad excitation continuum [L. Facheris et al., Phys. Rev. Lett. 129, 087201 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.087201] is shown to be a series of dispersive bound states reminiscent of "Zeeman ladders" in quasi-one-dimensional Ising systems. At wave vectors where interchain interactions cancel at the mean field level, they can indeed be interpreted as bound finite-width kinks in individual chains. Elsewhere in the Brillouin zone their true two-dimensional structure and propagation are revealed.

MeSH terms

  • Anisotropy
  • Memory*
  • Neutrons*
  • Reproduction