Abstract
The pyrochlore material Nd2Zr2O7 with an "all-in-all-out" (AIAO) magnetic order shows novel quantum moment fragmentation with gapped flat dynamical spin ice modes. The parametrized spin Hamiltonian with a dominant frustrated ferromagnetic transverse term reveals a proximity to a U(1) spin liquid. Here we study the magnetic excitations of Nd2Zr2O7 above the ordering temperature (TN) using high-energy-resolution inelastic neutron scattering. We find strong spin ice correlations at zero energy with the disappearance of gapped magnon excitations of the AIAO order. It seems that the gap to the dynamical spin ice closes above TN and the system enters a quantum spin ice state competing with and suppressing the AIAO order. Classical Monte Carlo simulations, molecular dynamics, and quantum boson calculations support the existence of a Coulombic phase above TN. Our findings relate the magnetic ordering of Nd2Zr2O7 with the Higgs mechanism and provide explanations for several previously reported experimental features.
| Original language | English |
|---|---|
| Article number | 097203 |
| Journal | Physical Review Letters |
| Volume | 124 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 6 2020 |
Funding
We thank K. Siemensmeyer, Y.-P. Huang, M. Hermele, S. T. Bramwell, and A. T. Boothroyd for helpful discussions on the related theory. This research was supported by the DFG through Project B06 of SFB 1143 (Project-id 247310070). This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Experiments at the ISIS Neutron and Muon Source were supported by a beam time allocation RB1810504 from the Science and Technology Facilities Council (DOI: 10.5286/ISIS. E.92924095).
| Funders | Funder number |
|---|---|
| Science and Technology Facilities Council | |
| Deutsche Forschungsgemeinschaft | 247310070, SFB 1143 |