Quantum dynamics and entanglement of spins on a square lattice

Niels Bech Christensen, Henrik Moodysson Rønnow, Desmond Francis McMorrow, A. Harrison, T.G. Perring, Mechtild Enderle, R. Coldea, L.P. Regnault, G. Aeppli

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    Abstract

    Bulk magnetism in solids is fundamentally quantum mechanical in nature. Yet in many situations, including our everyday encounters with magnetic materials, quantum effects are masked, and it often suffices to think of magnetism in terms of the interaction between classical dipole moments. Whereas this intuition generally holds for ferromagnets, even as the size of the magnetic moment is reduced to that of a single electron spin (the quantum limit), it breaks down spectacularly for antiferromagnets, particularly in low dimensions. Considerable theoretical and experimental progress has been made in understanding quantum effects in one-dimensional quantum antiferromagnets, but a complete experimental description of even simple two-dimensional antiferromagnets is lacking. Here we describe a comprehensive set of neutron scattering measurements that reveal a non-spin-wave continuum and strong quantum effects, suggesting entanglement of spins at short distances in the simplest of all two-dimensional quantum antiferromagnets, the square lattice Heisenberg system.
    Original languageEnglish
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume104
    Issue number39
    Pages (from-to)15264-15269
    ISSN0027-8424
    DOIs
    Publication statusPublished - 2007

    Cite this

    Christensen, N. B., Rønnow, H. M., McMorrow, D. F., Harrison, A., Perring, T. G., Enderle, M., Coldea, R., Regnault, L. P., & Aeppli, G. (2007). Quantum dynamics and entanglement of spins on a square lattice. Proceedings of the National Academy of Sciences of the United States of America, 104(39), 15264-15269. https://doi.org/10.1073/pnas.0703293104