Abstract
The Ce3+ pseudospin-1/2 degrees of freedom in the pyrochlore magnet Ce2Zr2O7 are known to possess dipole-octupole character, making it a candidate for novel quantum spin liquid ground states at low temperatures. We report new polarized neutron diffraction at low temperatures, as well as heat capacity (Cp) measurements on single crystal Ce2Zr2O7. The former bears both similarities and differences with that measured from the canonical dipolar spin ice compound Ho2Ti2O7, while the latter rises sharply at low temperatures, initially plateauing near 0.08 K, before falling off toward a high temperature zero beyond 3 K. Above∼0.5 K, the Cp dataset can be fit to the results of a quantum numerical linked cluster calculation, carried out to fourth order, that allows estimates for the terms in the near-neighbor XYZ Hamiltonian expected for such dipole-octupole pyrochlore systems. Fits of the same theory to the temperature dependence of the magnetic susceptibility and unpolarized neutron scattering complement this analysis. A comparison between the resulting best-fit numerical linked cluster calculation and the polarized neutron diffraction shows both agreement and discrepancies, mostly in the form of zone-boundary diffuse scattering in the non-spin-flip channel, which are attributed to interactions beyond near neighbors. The lack of an observed thermodynamic anomaly and the constraints on the near-neighbor XYZ Hamiltonian suggest that Ce2Zr2O7 realizes a U(1)π quantum spin liquid state at low temperatures, and one that likely resides near the boundary between dipolar and octupolar character.
| Original language | English |
|---|---|
| Article number | 021015 |
| Journal | Physical Review X |
| Volume | 12 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jun 2022 |
| Externally published | Yes |
Funding
We greatly appreciate the technical support from Alan Ye and Yegor Vekhov at the NIST Center for Neutron Research. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). We also acknowledge the support of both the Institut Laue-Langevin and the National Institute of Standards and Technology, U.S. Department of Commerce for neutron beam time as well as administrative and technical assistance during the course of our experiments. D. R. Y. and K. A. R. acknowledge the use of the Analytical Resources Core at Colorado State University. B. P. and R. S. acknowledge support by the Deutsche Forschungsgemeinschaft under Grant No. SFB 1143 (Project No. 247310070) and the cluster of excellence ct.qmat (EXC 2147, Project No. 390858490). Work at LANL was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (R. M.). We thank Paul McClarty for a critical reading of the manuscript.