Field-angle resolved magnetic excitations as a probe of hidden-order symmetry in CeB6

Abstract

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 compound CeB6 and 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 (AFQ) and field-induced octupolar (AFO) order. Here we present a combined experimental and theoretical investigation of collective excitations in the phase II of CeB6. 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 rotating field is calculated within a localized approach using the pseudo-spin presentation for the Gamma8 states. We show that the rotating-field technique at fixed momentum can complement conventional INS measurements of the dispersion at constant field and holds great promise for identifying the symmetry of multipolar order parameters and the details of inter-multipolar interactions that stabilize hidden-order phases.

15 pages with 13 figures + Supplemental Material

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Cited by in corpus (11)

• Multipolar ordering from dynamical mean field theory with application to CeB6
• Multiple-$q$ dipole-quadrupole instability in spin-1 triangular-lattice systems
• Melting of spin ice state and development of fifth order susceptibility with magnetic field in pyrochlore Tb2Sn2O7
• Cascade of magnetic-field-driven quantum phase transitions in Ce3Pd20Si6
• Local origin of the strong field-space anisotropy in the magnetic phase diagrams of Ce${}_{1-x}$La${}_x$B${}_6$ measured in a rotating magnetic field
• Topological paramagnetic excitons of localized f electrons on the honeycomb lattice
• Theory of Magnetoacoustic Resonance to Probe Multipole Effects Due to a Crystal Field Quartet
• Optical and magnetic excitations in the underscreened quasi-quartet Kondo lattice
• Isotropic parallel antiferromagnetism in the magnetic-field-induced charge-ordered state of SmRu${}_4$P${}_{12}$ caused by $p$-$f$ hybridization
• Symmetry Rules on Multipole Interactions under Crystallographic Point Groups and Application to Multiple-$Q$ Multipole States
• Novel Magnetoacoustic Resonance Technique for Exploring Hidden Quadrupoles in a Crystal Field Quartet