Raman spectroscopy off-electron metals: An example ofCeB6

Abstract

We performed an optical spectroscopy study of electronic and magnetic excitations for a rare-earth system with a single electron quasi-localized in the f -shell on an ion at high-symmetry crystallographic site in application to CeB6 heavy-fermion metal. We carried out group-theoretical classification of the electronic crystal field (CF) transitions and assessed their coupling to light cross-sections for polarization resolved Raman scattering processes. We discuss applicability of symmetrized Raman susceptibility to studies of exotic charge and spin high multiplet ordering phases in f -electron systems. We study temperature effects on intra-and inter-multiplet CF transitions and also on the coupling between the CF excitations with the lattice vibrations. We acquired temperature dependence of the low-frequency polarization resolved Raman response for all Raman-allowed symmetry channels: A1g, Eg, T1g, and T2g of the cubic O h point group. We demonstrate that T1g-symmetry static Raman susceptibility shows a temperature dependence which is consistent with the previouslyreported magnetic susceptibility data. Such behavior in the T1g channel signifies the presence of long wavelength magnetic fluctuations, which is interpreted as a manifestation of ferromagnetic correlations induced by tendency towards quadrupolar ordering.

Crystal-field excitations and quadrupolar fluctuations of 4f-electron systems studied by polarized light scattering

“…1(a) Inset]. Such behavior is a manifestation of Kondo effect, which shortens the lifetime of the excited CF states [12]. In TbInO 3 , the enhanced linewidth of the CF transitions within the 7 F 6 multiplet is associated with the the magnetic fluctuations near the spin-liquid ground state: the dynamics of the correlated yet nonordered magnetic moments manifests itself through the width of CF excitations.…”

“…2(a)], suggesting development of ferromagnetic (FM) correlations. The FM correlations are induced by the tendency towards AFQ ordering: as the orbits at neighboring Ce sites are quasi-degenerate, the intra-atomic Hund's rule favors the spins to be aligned [12]. For YbRu 2 Ge 2 , the FQ phase is a realization of electronic nematic states since the electronic properties spontaneously break the fourfold rotational symmetry of the tetragonal crystal.…”

Local origin of the strong field-space anisotropy in the magnetic phase diagrams of Ce1−xLaxB6 measured in a rotating magnetic field

“…We used a [CeB 24 ] 3+ cluster model with all boron atoms at the vertices of the truncated cube substituted by point charges of −1.5e. The charge value is picked empirically, so that the energy difference between the ground-state Γ 8 quartet and the excited Γ 7 doublet matches the energy of the Γ 8 → Γ 7 CEF transition (∼46 meV or 372 cm −1 at room temperature) observed with inelastic neutron scattering and Raman spectroscopy [81][82][83][84][85]. The obtained ab initio spin-orbit coupling (SOC) states were analyzed in terms of projection on the lowest-energy atomic multiplet (J = 5/2).…”

Crystal-field excitations and vibronic modes in triangular-lattice spin-liquid candidate TbInO$_3$

“…Unlabelled spectral features below 15 meV are related to crystal-field modes; some weak features at higher energy, for example those in between A 1 modes, result from second-order phonon scattering. In such scattering process, two phonons of zero total momentum are excited simultaneously; because the resulting spectral feature depends on the phonon dispersion and density of states, it does not have Lorentzian lineshape and commonly exhibits broad linewidth [24,25].…”