Abstract
Quantum spin liquid (QSL) is a disordered state of quantum-mechanically entangled spins commonly arising from frustrated magnetic dipolar interactions. However, QSL in some pyrochlore magnets can also come from frustrated magnetic octupolar interactions. Although the key signature for both dipolar and octupolar interaction-driven QSL is the presence of a spin excitation continuum (spinons) arising from the spin quantum number fractionalization, an external magnetic field-induced ferromagnetic order will transform the spinons into conventional spin waves in a dipolar QSL. By contrast, in an octupole QSL, the spin waves carry octupole moments that do not couple, in the leading order, to an external magnetic field or to neutron moments but will contribute to the field dependence of the heat capacity. Here we use neutron scattering to show that the application of a large external magnetic field to Ce2Zr2O7, an octupolar QSL candidate, induces an Anderson-Higgs transition by condensing the spinons into a static ferromagnetic ordered state with octupolar spin waves invisible to neutrons but contributing to the heat capacity. Our theoretical calculations also provide a microscopic, qualitative understanding for the presence of octupole scattering at large wave vectors in Ce2Sn2O7 pyrochlore, and its absence in Ce2Zr2O7. Therefore, our results identify Ce2Zr2O7 as a strong candidate for an octupolar U(1) QSL, establishing that frustrated magnetic octupolar interactions are responsible for QSL properties in Ce-based pyrochlore magnets.
| Original language | English |
|---|---|
| Article number | 094425 |
| Journal | Physical Review B |
| Volume | 106 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 1 2022 |
Funding
We are grateful to Romain Sibille and Petit Sylvain for providing us with raw data of powder results on and the Monte Carlo simulations for the octupole ice shown in Fig. . We thank Arthur Ramirez, Owen Benton, and Collin Broholm for helpful discussions. The neutron scattering work at Rice is supported by U.S. DOE BES DE-SC0012311 (P.D.). The theoretical work at Rice was supported by the National Science Foundation Division of Materials Research Award No. DMR-1917511 (H.Y. and A.H.N.). The single-crystal-growth work at Rice is supported by the Robert A. Welch Foundation under Grant No. C-1839 (P.D.). G.C. was support by the Research Grants Council of Hong Kong with General Research Fund Grant No. 17306520. E.M. acknowledges support from the Robert A. Welch Foundation under Grant No. C-2114 and C.-L.H. acknowledges the support from U.S. DOE BES DE-SC0019503. Crystal growth by B.G. at Rutgers was supported by the visitor program at the Center for Quantum Materials Synthesis (cQMS), funded by the Gordon and Betty Moore Foundation's EPiQS initiative through Grant No. GBMF10104, and by Rutgers University. Polycrystalline preparation by X.X. was supported by the DOE under Grant No. DOE DE-FG02-07ER46382. Research at ORNL's SNS was sponsored by the Scientific User Facilities Division, BES, U.S. DOE. Experiments at the ISIS Neutron and Muon Source were supported by a beamtime allocation from the Science and Technology Facilities Concil .
| Funders | Funder number |
|---|---|
| ISIS | |
| Scientific User Facilities Division | |
| U.S. DOE BES | DE-SC0012311 |
| U.S. Department of Energy | |
| Division of Materials Research | DMR-1917511 |
| Welch Foundation | C-1839 |
| Gordon and Betty Moore Foundation | GBMF10104 |
| Basic Energy Sciences | DE-SC0019503 |
| Rutgers, The State University of New Jersey | DOE DE-FG02-07ER46382 |
| Science and Technology Facilities Council | |
| Research Grants Council, University Grants Committee | 17306520, C-2114 |