Heavy Fermion Metal CeB6 in SubTHz and THz Range: The Electron Spin Resonance and Neutron Scattering Studies

• Published in: Applied magnetic resonance Vol. 52; no. 4; pp. 459 - 472
• Main Authors: Semeno, A. V., Okubo, S., Ohta, H., Demishev, S. V.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.04.2021; Springer Nature B.V
• Subjects: Antiferromagnetism; Atoms and Molecules in Strong Fields; Cerium; Crystal structure; Electric fields; Electron paramagnetic resonance; Electron spin; Electrons; Experiments; Fermions; Frequency ranges; Ground state; Inelastic scattering; Laser Matter Interaction; Low temperature; Magnetic fields; Magnetic properties; Neutron scattering; Neutrons; Organic Chemistry; Phase transitions; Physical Chemistry; Physics; Physics and Astronomy; Resonance scattering; Review; Solid State Physics; Spectroscopy/Spectrometry; Spin resonance; Temperature; Terahertz Spectroscopy
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-020-01274-2

Cerium hexaboride attracts attention of solid-state community for almost 50 years. Nowadays, this material is considered as a unique example of a system with orbital ordering resulting in formation of low-temperature magnetic phase with quadrupolar order, the so-called antiferroquadrupole phase. In crystal electric field 4f  1 state of Ce 3+ splits into Γ 7 doublet and Γ 8 quartet, the latter is believed to be the ground state, as long as just Γ 8 allows quadrupolar effects. An additional tool for studying rich physics of CeB 6 appeared since the discovery in this material the ESR, which is specific to antiferroquadrupole (AFQ) phase and is missing in the paramagnetic phase. In the present review, we have brought together electron spin resonance and inelastic neutron scattering data, which allowed obtaining most detailed structure of the magnetic resonance modes in the AFQ phase in a wide-frequency range up to 0.6 THz. It is shown that apart paramagnetic resonance main mode with homogeneous precession of the magnetization, there are antiferromagnetic resonance modes as well, some of them existing in the AFQ phase. Analysis of the g factors demonstrates that available theories based on Γ 8 ground state are facing difficulties with accounting experimental data, thus providing a challenge for developing of a theory correctly describing dynamic magnetic properties of this interesting material.