MAGNETORESISTANCE IN GDNI - MAGNETIC-POLARONIC-LIKE EFFECT NEAR THE CURIE-TEMPERATURE AND LOW-TEMPERATURE SIGN REVERSAL

The results of magnetoresistance (Delta rho/rho) measurements in GdNi, in the temperature range 4.2 to 300 K, an reported. The sign of Delta rho/rho above the Curie temperature (T-C=70 K) is negative and its ma gnitude in a magnetic field of 80 kOe grows with decreasing temperatur e below 150 K with a peak value of about -20% at T-C. These features, qualitatively resembling those in giant magnetoresistance systems (man ganates), are attributed to the formation of some kind of magnetic pol arons induced by Gd. The magnetoresistance changes sign below 12 K whi ch is attributed to subtle band-structure effects.