1. Fractional spinon excitations in the quantum Heisenberg antiferromagnetic chain
- Author
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Jean-Sébastien Caux, Henrik M. Rønnow, Mechthild Enderle, Anne Stunault, Martin Mourigal, A. Klöpperpieper, and Quantum Condensed Matter Theory (ITFA, IoP, FNWI)
- Subjects
Physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Statistical Mechanics (cond-mat.stat-mech) ,Condensed matter physics ,Spins ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Neutron scattering ,021001 nanoscience & nanotechnology ,01 natural sciences ,Spinon ,Inelastic neutron scattering ,3. Good health ,Condensed Matter - Strongly Correlated Electrons ,Quantum mechanics ,0103 physical sciences ,Quasiparticle ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Ground state ,Quantum ,Condensed Matter - Statistical Mechanics - Abstract
Assemblies of interacting quantum particles often surprise us with properties that are difficult to predict. One of the simplest quantum many-body systems is the spin 1/2 Heisenberg antiferromagnetic chain, a linear array of interacting magnetic moments. Its exact ground state is a macroscopic singlet entangling all spins in the chain. Its elementary excitations, called spinons, are fractional spin 1/2 quasiparticles; they are created and detected in pairs by neutron scattering. Theoretical predictions show that two-spinon states exhaust only 71% of the spectral weight while higher-order spinon states, yet to be experimentally located, are predicted to participate in the remaining. Here, by accurate absolute normalization of our inelastic neutron scattering data on a compound realizing the model, we account for the full spectral weight to within 99(8)%. Our data thus establish and quantify the existence of higher-order spinon states. The observation that within error bars, the entire weight is confined within the boundaries of the two-spinon continuum, and that the lineshape resembles a rescaled two-spinon one, allow us to develop a simple physical picture for understanding multi-spinon excitations., 22 pages, 4 figures, Supplementary materials
- Published
- 2013