MAGNETIC AND THERMODYNAMIC PROPERTIES OF CECU6-XAUX FOR 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-2

The Neel temperature T(N)(x) of the heavy-fermion alloys CeCu6-xAux exhibits a sharp maximum, T(N) = 2.2 K for x = 1, coinciding with a change of the lattice constant b(x) from a slight contraction for x < 1 to an expansion for x > 1. The samples remain single-phase orthorhombic (at room temperature) up to x = 1.4 after annealing at 700-degrees-C and up to x = 2 directly after preparation. Measurements of the specific heat indicate that C/T at low T shows a nonmonotonic behavior with a maximum at x almost-equal-to 0.25 and a minimum at x = 1. These extrema can be qualitatively understood by considering the contributions from Kondo quasiparticle and magnetic excitations.