We consider the leading nonanalytic temperature dependence of the specific heat and temperature and momentum dependence of the spin susceptibility for two-dimensional fermionic systems with noncircular Fermi surfaces. We demonstrate the crucial role played by Fermi surface curvature. For a Fermi surface with inflection points, we demonstrate that thermal corrections to the uniform susceptibility in $D=2$ change from ${\chi }_s\propto T$ to ${\chi }_s\propto T^{2∕3}$ for generic inflection points and to ${\chi }_s\propto T^{1∕2}$ for special inflection points along symmetry directions. Errors in previous work are corrected. An application of the results to ${\mathrm{Sr}}_2\mathrm{Ru}{\mathrm{O}}_4$ is given.

• Received 20 April 2006

DOI:https://doi.org/10.1103/PhysRevB.74.115119