Specific heat of the spin-triplet superconductor Sr2RuO4 with nonmagnetic impurities

We report the substitution effect of nonmagnetic Ti4+ for Ru4+ on the specific heat of Sr2Ru1-xTixO4 from x = 0 (spin-triplet superconductor) to 9% (magnetically ordered phase with glassy behavior) via magnetic instability point at x(c) similar to 2.5%. We found that specific heat divided by temperature C-p/T around x(c) deviates from the conventional Fermi liquid behavior seen in pure Sr2RuO4 and shows the logarithmic behavior at x(c). Such critical enhancement is attributable to the diverging two-dimensional antiferromagnetic fluctuation, which arises mainly from the nesting within one of the three Fermi-surface sheets. (C) 2003 Elsevier Science B.V. All rights reserved.