Light scattering in heavy fermion compounds

Abstract

We present results of Raman spectroscopy and magnetic susceptibility measurements in the actinide compounds UO 2, UPt 3 and UBel3. The differences in the degree of localization of the 5f-electrons in the insulating UO 2 and in the metallic, heavy fermion compounds UPt 3 and UBel3 are discussed. In both types of compounds we find evidence of localized electronic excitations, which yield a good fit of the magnetic susceptibility data. The spin relaxation rates of UPt 3 and UBel3 at q --0 are determined experimentally from the quasielastic light scattering.

First principles calculation of the elastic constants and phonon modes of UO2 using GGA + U with orbital occupancy control

“…Manara and Renker [21] measured the Raman spectra of a number of UO 2 /UO 2+x samples of differing stoichiometries and found that a peak around 1150 cm À1 was characteristic of stoichiometric UO 2 . This peak, also reported by Schoenes [33], Graves [28] and Blumenroeder et al [34], is attributed to a U 5 ? U 3 crystal field transition.…”

Raman spectroscopic studies of defect structures and phase transition in hyper-stoichiometric UO2+x

“…44 This is at odds with both Raman results and calculations, but the reason for this is unclear. This assignment of the Raman band has persisted, 43,[48][49][50][51] primarily since its intensity increased with a temperature decrease (I 300 K E 0.25I 20 K ), 44,49 which is not expected for pure multiphonon excitation, but attributable to a band of electronic scattering origin. 49,52 This reasoning can be supported by single crystal measurements.…”

Investigation of the skull melting method for the generation of particulate material of inorganic compounds

“…As the materials under consideration do not contain any ferromagnetic components, the relative permeability is assumed to be : r = 1. The molar susceptibility of UO 2 , which is directly coupled to the relative permeability, has been investigated by Blumenröder et al [8] for a temperature range 30 K #T # 400 K. For the available data of this temperature range the assumption is valid. The relative permittivity was investigated by Hampton et al in 1985 [9] at room temperature.…”