1. Fractional spinon excitations in the quantum Heisenberg antiferromagnetic chain.
- Author
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Mourigal, Martin, Enderle, Mechthild, Klöpperpieper, Axel, Caux, Jean-Sébastien, Stunault, Anne, and Rønnow, Henrik M.
- Subjects
- *
ANTIFERROMAGNETIC materials , *ANTIFERROMAGNETISM , *MAGNETIC materials , *NEUTRONS , *MAGNETISM - Abstract
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 created and detected in pairs by neutron scattering. Theoretical predictions show that two-spinon states exhaust only 71% of the spectral weight and 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 spin-1/2 Heisenberg antiferromagnetic chain compound, 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 experimental line shape resembles a rescaled two-spinon one with similar boundaries allows us to develop a simple picture for understanding multi-spinon excitations. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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