Large magnetoresistance and magnetocaloric effect above 70 K in Gd₂Co₂Al, Gd₂Co₂Ga, and Gd₇Rh₃

Abstract

The electrical resistivity, magnetization, and heat-capacity behavior of the Gd-based compounds, Gd₂Co₂Al, Gd₂Co₂Ga, and Gd₇Rh₃, ordering magnetically at T_C=78 K, T_C=76 K, and T_N=140 K, have been investigated as a function of temperature and magnetic field. All these compounds are found to show large magnetoresistance (with a negative sign) in the paramagnetic state at rather high temperatures with the magnitude peaking at respective magnetic ordering temperatures. There is a corresponding behavior in the magnetocaloric effect as inferred from the entropy derived from these data.