The magnetoresistance in GdNi: Magnetic-polaronic-like effect near Curie temperature and low temperature sign reversal

TL;DR

This study investigates the magnetoresistance behavior in GdNi across a wide temperature range, revealing magnetic-polaronic effects near the Curie temperature and a low-temperature sign reversal linked to band structure changes.

Contribution

It reports the first detailed measurement of magnetoresistance in GdNi, highlighting magnetic-polaronic effects and sign reversal phenomena near and below the Curie temperature.

Findings

Negative magnetoresistance above Tc with a peak at Tc

Sign reversal of magnetoresistance below 12 K

Magnetic-polaronic effects induced by Gd

Abstract

The results of magnetoresistance ($\Delta \rho /\rho$)measurements in GdNi, in the temperature range 4.2 to 300 K are reported. The sign of $\Delta \rho /\rho $ above the Curie temperature (Tc= 70 K) is negative and its magnitude in a magnetic field of 80kOe grows with decreasing temperature below 150 K with a peak value of about -20% at Tc. These features, qualitatively resembling those in giant magnetoresistance systems (manganates), are attributed to the formation of some kind of magnetic polarons induced by Gd. The magnetoresistance changes sign below 12 K which is attributed to subtle band structure effects.