Spin Fluctuation and Magnetic Phase Transition in Itinerant Heavy Electron System Ce(Ru _1-xRh_x) ₂Si ₂ (x = 0, 0.03 and 0.05)

The specific heats and the susceptibilities of Ce(Ru1-xRhx)(2)Si-2 single crystals (x = 0, 0.03 and 0.05) were studied between 0.1 and 10 K. The magnetic ground state of Ce(Ru1-xRhx)(2)Si-2 is found to be a Fermi liquid even near the critical concentration x = 0.03. x = 0.05 compound takes place a spin density wave transition at around 2 K, which is an antiferromagnetic order of itinerant heavy electrons by nesting in the Fermi liquid state. The low temperature behavior of the specific heat and the susceptibility were well explained by the effect of spin fluctuations based on the SCR theory.