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

The modified FeRh compounds with iron atoms partly substituted for nic kel and with rhodium atoms substituted for palladium and iridium were systematically studied by means of magnetization, electrical resistivi ty, magnetoresistance and specific heat measurements. The magnetic sta te and electrical properties of FeRh-based compounds are strongly affe cted by the substitution owing to the electronic origin of magnetic ph ase transitions in these compounds. The field-induced first-order tran sitions from antiferromagnetic (AF) to ferromagnetic (F) state are acc ompanied by giant magnetoresistance (Delta rho/rho down to -88%) and b y a change in the electronic specific heat coefficient gamma from gamm a(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 disa ppearance of superzones and the energy gap on superzone boundaries. Th e magnetic phase diagrams for (Fe1-xNix)Rh and for Fe(Rh1-xPdx) are de termined.