Measurements of magnetic susceptibility x(T), specific heatC(T), Hall coefficient RH(T), and Yb valence n521n f @ f -occupation number n f (T) determined from Yb LIII x-ray absorption measurements# were carried out on single crystals of Yb12xLuxAl3. The low-temperature anomalies observed in x(T) and C(T) corresponding to an energy scale Tcoh;40 K in the intermediate valence, Kondo lattice compound YbAl3 are suppressed by Lu concentrations as small as 5% suggesting these low-T anomalies are extremely sensitive to disorder and, therefore, are a true coherence effect. By comparing the temperature dependence of various physical quantities to the predictions of the Anderson impurity model, the slow crossover behavior observed in YbAl3, in which the data evolve from a low-temperature coherent, Fermi-liquid regime to a high-temperature local moment regime more gradually than predicted by the Anderson impurity model, appears to evolve to fast crossover behavior at x;0.7 where the evolution is more rapid than predicted. These two phenomena found in Yb12xLuxAl3, i.e., the low-T anomalies and the slow/fast crossover behavior are discussed in relation to recent theories of the Anderson lattice.
[1]
P. Anderson.
Valence Instabilities and Related Narrow-Band Phenomena
,
1994
.
[2]
Alex C. Hewson,et al.
The Kondo Problem to Heavy Fermions
,
1993
.
[3]
M. Springford.
The Kondo problem to heavy fermions
,
1993
.
[4]
L. M. Falicov,et al.
Valence fluctuations in solids : Santa Barbara Institute for Theoretical Physics Conferences, Santa Barbara, California, January 27-30, 1981
,
1981
.
[5]
R. Parks.
Valence Instabilities and Related Narrow-Band Phenomena
,
1977
.