MAGNETIC BEHAVIOR AND VALENCE TRANSITION OF Ce IN Ce_1−xLa_xNi

Evolution of Ce dynamic magnetic response in Ce 1 − x La x Ni compounds

“…The increase of the quasielastic line-width (for x = 0.2 and x = 0.5) gives evidence for the growth of the Kondo temperature and, consequently, the hybridization energy, as the Ce concentration increases. This conclusion is consistent with results obtained from a variation of the temperature dependence of the heat capacity [5] and the magnetic susceptibility with concentration [8]. CeNi has a gap-like spectrum, which distinguishes from spectra obtained for Ce-based intermetallic IV compounds.…”

“…The use of the RE-Ni distance as a physical parameter allows to represent the effect of variation of lattice spacing by only one parameter for compounds of low crystal symmetry. The different linear slopes of the RE-Ni distance plotted as a function of La concentration for x < 0.3 and x > 0.5 prove the existence of a transformation from IV to Kondo state for x ∼ 0.5, as suggested in [5], [8]. It is noteworthy that the change of slope at different temperatures occurs at nearly the same value of RE-Ni distance.…”

“…The Ce valence at 77 K is estimated to be 3.15 from X-ray absorption spectroscopy [6], but this value is very sensitive to both pressure [7] and temperature [6]. Doping CeNi with La corresponds to applying a "negative" pressure and induces a transition to an integer valence state [8]. The ionic contribution to the CF potential at the Ce ion site is determined mainly by the nearest-neighbor Ce environment, which is formed by seven Ni ions.…”