Crystal-field states and defect levels in candidate quantum spin ice Ce2Hf2O7

Victor Porée (1) , Elsa Lhotel (2) , Sylvain Petit (3, 4) , Aleksandra Krajewska (5) , Pascal Puphal (6) , Adam H. Clark (7) , Vladimir Pomjakushin (1) , Helen C. Walker (5) , Nicolas Gauthier (8) , Dariusz J. Gawryluk (6) , Romain Sibille (1)

1 LNS - Laboratory for Neutron Scattering and Imaging [Paul Scherrer Institute]
2 NEEL - MagSup - Magnétisme et Supraconductivité
3 LLB - UMR 12 - Laboratoire Léon Brillouin
4 NFMQ - LLB - Nouvelles frontières dans les matériaux quantiques
5 ISIS - ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ISIS Neutron and Muon Source
6 PSI - Paul Scherrer Institute
7 Max Planck Institute for Solid State Research
8 SLAC - SLAC National Accelerator Laboratory

We report the synthesis of powder and single-crystal samples of cerium pyrohafnate and their characterization using neutron diffraction, thermogravimetry and x-ray absorption spectroscopy. We evaluate the amount of nonmagnetic ${\mathrm{Ce}}^{4+}$ defects and use this result to interpret the spectrum of crystal-electric field transitions observed using inelastic neutron scattering. The analysis of these single-ion transitions indicates the dipole-octupole nature of the ground-state doublet and a significant degree of spin-lattice coupling. The single-ion properties calculated from the crystal-electric field parameters obtained spectroscopically are in good agreement with bulk magnetic susceptibility data down to about 1 K. Below this temperature, the behavior of the magnetic susceptibility indicates a correlated regime without showing any sign of magnetic long-range order or freezing down to 0.08 K. We conclude that ${\mathrm{Ce}}_2{\mathrm{Hf}}_2{\mathrm{O}}_7$ is another candidate to investigate exotic correlated states of quantum matter, such as the octupolar quantum spin ice recently argued to exist in the isostructural compounds ${\mathrm{Ce}}_2{\mathrm{Sn}}_2{\mathrm{O}}_7$ and ${\mathrm{Ce}}_2{\mathrm{Zr}}_2{\mathrm{O}}_7$.

Domaines: Matière Condensée [cond-mat]

Victor Porée, Elsa Lhotel, Sylvain Petit, Aleksandra Krajewska, Pascal Puphal, et al.. Crystal-field states and defect levels in candidate quantum spin ice Ce2Hf2O7. Physical Review Materials, 2022, 6 (4), pp.044406. ⟨10.1103/PhysRevMaterials.6.044406⟩. ⟨hal-03644386⟩