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

• Published in: Physical review materials 2022-04, Vol.6 (4)
• Main Authors: Porée, Victor, Lhotel, Elsa, Petit, Sylvain, Krajewska, Aleksandra, Puphal, Pascal, Clark, Adam H., Pomjakushin, Vladimir, Walker, Helen C., Gauthier, Nicolas, Gawryluk, Dariusz J., Sibille, Romain
• Format: Article
• Language: English
• Subjects: Condensed Matter; Physics
• ISSN: 2475-9953
• DOI: 10.1103/PhysRevMaterials.6.044406

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 Ce4+ 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 Ce2Hf2 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 Ce2Sn2 O 7 and Ce2Zr2 O 7.