Pressure dependence of the Curie temperature of intermetallic compounds of iron and rare-earth elements, Th and Zr

The pressure dependence of the Curie temperature (Tc) of several intermetallic compounds of iron has been determined by means of the temperature dependence of the electrical resistivity at various pressures. Pressures up to 40 kbar were applied. The value of dTc/dp was observed to be negative in the compounds R2Fe17 (R=Pr,Nd,Er, and Th), Y6Fe23, Er6Fe23, ErFe3, Th2Fe7, ThFe3, CeFe2, and ZrFe2. The Curie temperature of the compound ThFe5 is pressure independent within experimental error. In the compounds RFe2 (R=Gd,Ho,Er, and Y), the value of dTc/dp was found to be positive. The experimental data are discussed in terms of Friedel's semilocalized model and the collective electron model.