Ruderman-Kittel-Kasuya-Yosida interaction and the paramagnetic properties ofRZn2intermetallic compounds

An extended form of the simple Ruderman-Kittel-Kasuya-Yosida theory which approximates the $s-f$ exchange integral by the form factor of the local-moment density and considers the interelectron interaction between conduction electrons in a simple manner is developed and found to predict correctly the positive sign of the paramagnetic Curie temperatures of $R{\mathrm{Zn}}_2$ ($R$ is a rare earth) intermetallic compounds. The use of this form of the indirect exchange interaction, apparently, does away with the need for locating an effective Fermi wave vector as is found necessary when the simple theory is used.