ELECTRICAL-RESISTIVITY AND MAGNETIC PHASE-TRANSITIONS IN MODIFIED FERH COMPOUNDS

The modified FeRh compounds with iron atoms partly substituted for nickel and with rhodium atoms substituted for palladium and iridium were systematically studied by means of magnetization, electrical resistivity, magnetoresistance and specific heat measurements. The magnetic state and electrical properties of FeRh-based compounds are strongly affected by the substitution owing to the electronic origin of magnetic phase transitions in these compounds. The field-induced first-order transitions from antiferromagnetic (AF) to ferromagnetic (F) state are accompanied by giant magnetoresistance (Delta rho/rho down to -88%) and by a change in the electronic specific heat coefficient gamma from gamma(AF)approximate to 35 mJ kg(-1) K-2 UP to gamma(F) approximate to 79 mJ kg(-1) K-2. This behaviour is connected with the appearance or disappearance of superzones and the energy gap on superzone boundaries. The magnetic phase diagrams for (Fe1-xNix)Rh and for Fe(Rh1-xPdx) are determined.