PRESSURE-DEPENDENT AND FIELD-DEPENDENT BEHAVIOR OF YBCU4AU

Temperature- and pressure-dependent measurements of the electrical res istivity rho(T,p) of the ternary compound YbCu4Au have been performed. These investigations yield an increase of the antiferromagnetic trans ition temperature T(N) from 0.6 K at ambient pressure up to more than 2 K at 50 kbar. The bulk modulus has been determined (B(o) almost-equa l-to 1.4 Mbar) at room temperature which together with partial derivat ivesT(N)/partial derivativep almost-equal-to 0.044 K/kbar derived from rho(T,p) allows an estimation of the Gruneisen constant OMEGA(T(N)) a lmost-equal-to 60. A study of the field-dependent behavior of the spec ific heat justifies an antiferromagnetic ground state. In the scope of an empirical model, the Kondo temperature T(K) of YbCu4Au was obtaine d to be 1.65 K, which is significantly smaller than the energy of the first excited crystal-field level above the ground-state doublet.