CECO0.89GE2 - A HEAVY-FERMION SYSTEM

The low-temperature (1.3-20 K) high-magnetic-field (0-10 T) heat capacity and magnetic susceptibility (1.5-300 K) of the CeCo0.89Ge2 and LaCo0.96Ge2 compounds have been measured. LaCo0.96Ge2 exhibits normal metallic behavior, while the cerium-containing compound shows (1) an enhanced value of zero-field electronic-specific-heat coefficient [gamma = 128 mJ/mol(Ce) K2], which increases significantly in high magnetic fields; (2) the absence of magnetic ordering down to 1.5 K; (3) a large and negative value of paramagnetic Curie temperature (-95.9 K); and (4) a large magnetic susceptibility at low temperature (9 X 10(-3) emu/mol at 1.7 K). All of these properties are evidence of high density of states at the Fermi level in CeCo0.89Ge2. Neither compound is superconducting down to 1.3 K, nor do they order magnetically.