Heat-capacity and magnetoresistance anomalies in Gd alloys

Abstract

The Gd contribution to heat-capacity (C_m) in the alloys, Gd_0.4Y_0.6Ni₂Si₂ and Gd_0.2La_0.8Cu₂Si₂, shows a gradual increase over a very wide temperature range before the onset of long range magnetic order. There is a tendency of isothermal magnetization data above 5 K to saturate with the application of the magnetic field. The results bring out the role of short-range ferromagnetic correlations on the heavy-fermion-like C_m anomaly even at temperatures far above 2T_N. The magnetoresistance (Δϱ/ϱ) behaviour of the alloys, Gd_1-xY_xNi₂Si₂, indicate the existence of spin fluctuation effects in the transition metal d bands, induced by Gd 4f magnetic moment. Relevance of these observations to the current trends in the field of heavy-fermion physics is brought out.