Anomalous Magnetic Phase Diagram of Ce(Rh_1-x}Co_x)₂Ge₂

Abstract

We have investigated low-temperature magnetic properties of Ce(Rh_1-xCo_x)₂Ge₂ (0≤ x≤ 1) by the measurements of the specific heat, the magnetic susceptibility and the magnetization, and obtained an anomalous magnetic phase diagram: CeRh₂Ge₂ exhibited two magnetic transitions at 14.5 and 8.9, K. Both transition temperatures almost linearly decrease with the Co substitution up to x-- 0.3 and finally disappear at x-- 0.75 following a little hump centered around x-- 0.5. This interesting phase diagram is discussed in the framework of Doniach's model.