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arXiv · 2301.13596

Confinement of fractional excitations in a triangular lattice antiferromagnet

L. Facheris·S. D. Nabi·A. Glezer Moshe·U. Nagel·T. Rõõm·K. Yu. Povarov·J. R. Stewart·Z. Yan·A. Zheludev
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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 [Phys. Rev. Lett. 129, 087201 (2022)] is shown to be a series of dispersive bound states reminiscent of "Zeeman ladders" in quasi-one-dimensional Ising systems. At wave vectors where inter-chain 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.

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L. Facheris, S. D. Nabi, A. Glezer Moshe, U. Nagel, T. Rõõm, K. Yu. Povarov, J. R. Stewart, Z. Yan, A. Zheludev. 2023-01-31. Confinement of fractional excitations in a triangular lattice antiferromagnet. https://doi.org/10.1103/physrevlett.130.256702

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