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arXiv · 2305.08261

Dipolar-octupolar correlations and hierarchy of exchange interactions in Ce$_2$Hf$_2$O$_7$

Victor Porée·Anish Bhardwaj·Elsa Lhotel·Sylvain Petit·Nicolas Gauthier·Han Yan·Vladimir Pomjakushin·Jacques Ollivier·Jeffrey A. Quilliam·Andriy H. Nevidomskyy·Hitesh J. Changlani·Romain Sibille
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Abstract

High-resolution neutron spectroscopy on Ce$_2$Hf$_2$O$_7$ 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, $J_{x}$ or $J_{y}$, with substantial dipolar $J_{z}$ and minute dipole-octupole $J_{xz}$ couplings. The $J_{xz}$ 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. Ce$_2$Hf$_2$O$_7$ 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.

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Victor Porée, Anish Bhardwaj, Elsa Lhotel, Sylvain Petit, Nicolas Gauthier, Han Yan, Vladimir Pomjakushin, Jacques Ollivier, Jeffrey A. Quilliam, Andriy H. Nevidomskyy, Hitesh J. Changlani, Romain Sibille. 2023-05-14. Dipolar-octupolar correlations and hierarchy of exchange interactions in Ce$_2$Hf$_2$O$_7$. https://doi.org/10.1103/j451-ztvr

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