High-resolution neutron spectroscopy on Ce2Hf2O7 reveals a correlated state characterized by distinct dipolar scattering signals -- quasi-elastic and inelastic contributions consistent with `photon' and `spinon' excitations in quantum spin ice. These signals coexist with weak octupolar scattering. Fits of thermodynamic data using numerical methods indicate a dominant octupolar exchange, Jx or Jy, with substantial dipolar Jz and minute dipole-octupole Jxz couplings. The Jxz value is corroborated by an independent fit of the neutron scattering amplitude balance between dipolar and octupolar `photon' contributions, highlighting its importance to understand neutron scattering results in this family. Ce2Hf2O7 enriches the landscape of dipole-octupole pyrochlore physics, and reveals a `quantum multipolar liquid' where hybrid correlations involve multiple terms in moment series expansion, opening questions on their intertwining and hierarchy in quantum phases.
@article{arxiv.2305.08261,
title = {Dipolar-octupolar correlations and hierarchy of exchange interactions in Ce$_2$Hf$_2$O$_7$},
author = {Victor Porée and Anish Bhardwaj and Elsa Lhotel and Sylvain Petit and Nicolas Gauthier and Han Yan and Vladimir Pomjakushin and Jacques Ollivier and Jeffrey A. Quilliam and Andriy H. Nevidomskyy and Hitesh J. Changlani and Romain Sibille},
journal= {arXiv preprint arXiv:2305.08261},
year = {2025}
}