In zero field, ${\mathrm{Ce}}_2{\mathrm{IrIn}}_8$ obeys Landau’s Fermi-liquid model, with a constant $C/T$ of about 700 mJ/Ce mol ${\mathrm{K}}^2$ below 0.7 K and a susceptibility that is constant to ±4% below 4 K. In applied magnetic field, however, ${\mathrm{Ce}}_2{\mathrm{IrIn}}_8$ shows definite non-Fermi-liquid (nFl) behavior at ∼13 T, with $C/T\sim \ln T$ between 0.3 and 6 K, $\chi \sim \ln T,$ and $\rho ={\rho }_0{+AT}^1.$ At fields of 17 T and higher there is a strong divergent upturn in $C/T$ below 0.7 K that is approximately field independent and the susceptibility becomes again constant (Fermi-liquid like) below 6 K and decreases in magnitude at low temperature compared to χ (13 T). These results imply that a quantum critical point may exist in ${\mathrm{Ce}}_2{\mathrm{IrIn}}_8$ at ∼13 T. The magnetization at low temperature as a function of field of ${\mathrm{Ce}}_2{\mathrm{IrIn}}_8$ between 0.1 and 30 T shows no sign of an increase, or jump, near 13 T, but rather a change from $M\sim H$ at lower fields to a more saturated behavior above 13 T. Thus, unlike previous field-induced nFl behavior, where the magnetic interactions responsible for the nFl behavior either came (i) at the field, $H_{\mathrm{metamag}},$ where the magnetization showed a step at a metamagnetic transition (e.g., in ${\mathrm{UPt}}_3$ or in ${\mathrm{Sr}}_3{\mathrm{Ru}}_2{\mathrm{O}}_7),$ or (ii) at the field where $T_{\mathrm{N}\mathrm{é}\mathrm{el}}$ in an antiferromagnet was suppressed to $T=0\mathrm{}$ by the field (e.g., in ${\mathrm{CeCu}}_{6-x}{\mathrm{Ag}}_x),$ the present measurements point to a different kind of behavior. Thus the nFl behavior in ${\mathrm{Ce}}_2{\mathrm{IrIn}}_8$ may be describable as due to quantum criticality at the point in the phase diagram where field induces magnetism. Comparisons to other nFl systems, both field-induced and those which display an anomalous upturn in $C/T$ at low temperatures, are made.

• Received 2 December 2002

DOI:https://doi.org/10.1103/PhysRevB.69.024402