Pressure-induced non-Fermi-liquid behavior in a heavy-fermion compoundCe7Ni3around the antiferromagnetic instability

Under increasing pressure, the Néel temperature of the heavy-fermion compound ${\mathrm{Ce}}_7$ ${\mathrm{Ni}}_3$ (${\mathrm{T}}_{\mathrm{N}}$=1.9 K for P=0) decreases and vanishes near ${\mathrm{P}}_{\mathrm{c}}$≈0.33 GPa. Non-Fermi-liquid behavior appears at 0.4 GPa in both the specific heat and ac magnetic susceptibilitiy, ${\mathrm{C}}_{\mathrm{m}}$/T∼-lnT and ${\mathrm{\chi }}_{\mathrm{ac}}$∝(1-α${\mathrm{T}}^{1\mathrm{/}2}$). Above 0.62 GPa, the normal Fermi-liquid state recovers, as indicated by the T independence of ${\mathrm{C}}_{\mathrm{m}}$T and the ${\mathrm{T}}^2$ dependence of the magnetic resistivity. The observed crossover with pressure is described by self-consistent renormalization theory of spin fluctuations (SF) in terms of the characteristic SF temperature ${\mathrm{T}}_0$ which increases by a factor of 20 for 0.33⩽P⩽0.75 GPa.