Correlated Quantum Tunnelling of Monopoles in Spin Ice

ORAL

Abstract

The spin ice materials Ho2Ti2O7 and Dy2Ti2O7 are by now perhaps the best-studied classical frustrated magnets. A crucial step towards the understanding of their low temperature behaviour – both regarding their unusual dynamical properties and the possibility of observing their quantum coherent time evolution – is a quantitative understanding of the spin-flip processes which underpin the hopping of magnetic monopoles. We attack this problem in the framework of a quantum treatment of a single ion subject to the crystal, exchange and dipolar fields from neighbouring ions. By studying the fundamental quantum mechanical mechanisms, we discover a bimodal distribution of hopping rates which depends on the local spin configuration, in broad agreement with rates extracted from experiment. Applying the same analysis to Pr2Sn2O7 and Pr2Zr2O7, we find an even more pronounced separation of time scales signalling the likelihood of coherent many-body dynamics
that is likely to have signatures in the behaviour of these systems.

–

Presenters

  • Bruno Tomasello

    Theory Group, Institut Laue-Langevin

Authors

  • Bruno Tomasello

    Theory Group, Institut Laue-Langevin

  • Claudio Castelnovo

    Cavendish Laboratory, University of Cambridge, TCM, University of Cambridge, Dept of Physics, University of Cambridge, University of Cambridge, Physics, Cambridge University

  • Roderich Moessner

    Max Planck Institute for the Physics of Complex Systems, MPIPKS Dresden, MPIpks, Max Planck Institut, Max Planck Institute for the Physics of Complex Systems, Dresden, Max-Planck-Institut fur Physik komplexer Systeme, MPI-PkS Dresden, Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden, Germany

  • Jorge Quintanilla

    SPS, University of Kent, School of Physical Sceinces, University of Kent, Canterbury, UK, Physics, University of Kent, University of Kent