Field-Angle-Resolved Magnetic Excitations as a Probe of Hidden-Order Symmetry in CeB6

• Published in: Physical review. X Vol. 10; no. 2
• Main Authors: Portnichenko, P Y, Akbari, A, Nikitin, S E, Cameron, A S, Dukhnenko, A V, Filipov, V B, N. Yu. Shitsevalova, Čermák, P, Radelytskyi, I, Schneidewind, A, Ollivier, J, Podlesnyak, A, Huesges, Z, J. Xu, Ivanov, A, Sidis, Y, Petit, S, J.-M. Mignot, Thalmeier, P, Inosov, D S
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 01.04.2020
• Subjects: Dispersion; Excitation spectra; Fermions; Inelastic scattering; Interaction models; Long range order; Magnetic fields; Magnetism; Momentum; Multipoles; Neutron scattering; Neutrons; Order parameters; Parameter identification; Quadrupoles; Rotation; Symmetry
• ISSN: 2160-3308
• DOI: 10.1103/PhysRevX.10.021010

In contrast to magnetic order formed by electrons’ dipolar moments, ordering phenomena associated with higher-order multipoles (quadrupoles, octupoles, etc.) are more difficult to characterize because of the limited choice of experimental probes that can distinguish different multipolar moments. The heavy-fermion compoundCeB6and its La-diluted alloys are among the best-studied realizations of the long-range-ordered multipolar phases, often referred to as “hidden order.” Previously, the hidden order in phase II was identified as primary antiferroquadrupolar and field-induced octupolar order. Here, we present a combined experimental and theoretical investigation of collective excitations in phase II ofCeB6. Inelastic neutron scattering (INS) in fields up to 16.5 T reveals a new high-energy mode above 14 T in addition to the low-energy magnetic excitations. The experimental dependence of their energy on the magnitude and angle of the applied magnetic field is compared to the results of a multipolar interaction model. The magnetic excitation spectrum in a rotating field is calculated within a localized approach using the pseudospin representation for theΓ8states. We show that the rotating-field technique at fixed momentum can complement conventional INS measurements of the dispersion at a constant field and holds great promise for identifying the symmetry of multipolar order parameters and the details of intermultipolar interactions that stabilize hidden-order phases.