The normal states of magnetic d and f transition metals

The normal states of magnetic metals with vanishing Curie (T sub c ) or Neel (T sub N ) temperatures are investigated by means of measurements of the temperature and pressure dependence of the resistivity in the stoichiometric d and f compounds MnSi, ZrZn sub 2 , CePd sub 2 Si sub 2 and CeNi sub 2 Ge sub 2 . The results for the nearly ferromagnetic d metals may be described over a wide range in temperature and pressure in terms of a quantitative model of a marginal Fermi liquid based on dispersive spin-fluctuation spectra inferred from inelastic neutron scattering data. The behaviour of the antiferromagnetic f metals is also unconventional, but in a way which cannot yet be readily categorized. Near the critical pressure where T sub N - > 0 K. CePd sub 2 Si sub 2 displays a resistivity of the form rho approxT exp 1.2plus/minus0.1 over nearly two decades in temperature before condensing into a short-coherence-length superconducting state below 0.4 K. The isoelectronic and isostructural compound CeNi sub 2 Ge sub 2 , with a lattice cell volume slightly smaller than that of CePd sub 2 Si sub 2 , remains normal down to 20 mK and shows a resistivity of the form rho approxT exp 1.4plus/minus0.1 over a decade below several kelvin at ambient pressure. These findings for the Ce systems have not yet been described consistently in terms of an extension of the model developed for the ferromagnetic d metals.