Heavy non-Fermi-liquid behavior in nearness to ferromagnetism in Th{sub 1{minus}x}U{sub x}Cu{sub 2}Si{sub 2}

Th{sub 1{minus}x}U{sub x}Cu{sub 2}Si{sub 2} compounds have been investigated by means of specific heat, susceptibility, magnetization, and resistivity measurements. Samples with x{ge}0.15 are ferromagnetic. Th{sub 0.85}U{sub 0.15}Cu{sub 2}Si{sub 2} and Th{sub 0.8}U{sub 0.2}Cu{sub 2}Si{sub 2} show enhanced values for C/T at low temperatures ({approx}460 mJ/UmolK{sup 2} for x=0.2). The specific heat of samples that exhibit no long-range order (x{le}0.1) can be described by C/T{proportional_to}{minus}ln(T). This divergence is characteristic of non-Fermi-liquid (nFl) systems. The results are discussed in regard to the current investigations on non-Fermi liquids. One interpretation of non-Fermi-liquid behavior is a T=0 instability in nearness to magnetism. Our data indicate that this is a system that displays C/T{proportional_to}lnT near to ferromagnetism. {copyright} {ital 1997} {ital The American Physical Society}