Low-temperature properties of YbCo2Ge2

The low-temperature properties of YbCo2Ge2 are studied by means of magnetic susceptibility chi, specific heat C-p and electrical resistivity rho measu rements under pressure. chi(T) follows a Curie-Weiss law with an effective magnetic moment corresponding to trivalent Yb-ions but deviates from this b ehavior below 100 K, The low-temperature value C-p/T = 215 mJ/mol K-2 is on e of the largest among known non-magnetic Yb-based compounds. rho(T) shows coherence effects below 100 K and a rapid response to external pressure. Th ese results allow to deduce the value of the characteristic temperature of the f-electrons as To < 100 K and suggest that YbCo2Ge2 is a moderate mixed -valent: compound close to being magnetic (C) 1999 Elsevier Science B.V. Al l rights reserved.