  Precision measurements of the Hall effect have been carried out for both
archetypal heavy fermion compound - CeCu6 and exemplary solid solutions
CeCu6-xAux (x= 0.1 and 0.2) with quantum critical behavior. The experimental
results have been obtained by technique with a sample rotation in magnetic
field in the temperature range 1.8-300K. The experiment revealed a complex
activation type dependence of the Hall coefficient RH(T) in CeCu6 with
activation energies Ea1/kB = 110K and Ea2/kB = 1.5K in temperature ranges
50-300K and 3-10K, respectively. Microscopic parameters of charge carriers
transport (effective masses, relaxation time) and localization radii ap1,2* of
heavy fermions (ap1*(T>50K)= 1.7 A and ap2*(T<20K)= 14 A) were estimated for
CeCu6. The second angular harmonic contribution has been established in the
Hall voltage of CeCu5.9Au0.1 and CeCu6 at temperatures below T*=24K. A
hyperbolic type divergence of the second harmonic term in Hall effect RH2(T)=
C(1/T-1/T*) at low temperatures is found to be accompanied with a power-law
behavior RH(T)= T -0.4 of the main contribution in the Hall coefficient for
CeCu5.9Au0.1 compound with quantum critical behavior.
