Field-Induced Quantum Criticality in a Two-Dimensional Antiferromagnet

ORAL

Abstract

We describe neutron scattering measurements on the two-dimensional spin gap antiferromagnet piperanzium hexachlorodicuprate (PHCC) in the vicinity of quantum critical point at which the spin gap is closed by an applied magnetic field. We measure the energy and damping of the propagating $S_z=1$ mode above the spin gap; both quantities become strongly temperature dependent at the critical field. The temperature dependence of the mode energy is successfully described by a self-consistent Hartree-Fock theory of interacting spin excitations.

*Work at the Johns Hopkins University was supported by the NSF under Grants No. DMR-0306940. Work at Harvard University was supported by NSF under Grants No. DMR-0537077. Work at NCNR was supported by NSF under Grants No. DMR-0086210

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Authors

  • Tao Hong

  • Michel Kenzelmann

  • Matthew Bouloubasis

  • Daniel Reich

    • The Johns Hopkins University
    • Johns Hopkins University

  • Collin Broholm

    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
    • Johns Hopkins University
    • Department of Physics and Astronomy, Johns Hopkins University

  • Matthew Stone

    • Oak Ridge National Laboratory

  • Emily Dunkel

  • Subir Sachdev

    • Harvard University
    • Harvard University, Department of Physics
    • Department of Physics, Harvard University