Quasiparticle breakdown in the quantum pyrochlore Yb2Ti2O7 in magnetic field

          @misc{ scivideos_PIRSA:17060034,
            doi = {10.48660/17060034},
            url = {https://pirsa.org/17060034},
            author = {Coldea, Radu},
            keywords = {Quantum Matter},
            language = {en},
            title = {Quasiparticle breakdown in the quantum pyrochlore Yb2Ti2O7 in magnetic field},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2017},
            month = {jun},
            note = {PIRSA:17060034 see, \url{https://scivideos.org/pirsa/17060034}}
          }
          

Abstract

The pyrochlore magnet Yb2Ti2O7 has the remarkable property that it orders magnetically, but has no propagating magnons over wide regions of reciprocal space. Using inelastic neutron scattering we observe that at high magnetic fields, in addition to dispersive magnons there is also a two-magnon continuum, which grows in intensity upon reducing field, overlaps with one-magnon states at intermediate fields leading to strong dispersion renormalizations and magnon decays. We re-evaluate the Hamiltonian finding dominant quantum exchange terms, which we propose are responsible for the anomalously strong quantum fluctuation effects observed at low fields.