POSSIBLE EVIDENCE FOR AN ENERGY-GAP BELOW THE NEEL TEMPERATURE IN TERNARY RARE-EARTH COMPOUNDS

Electrical-resistivity (rho) behavior in the vicinity of the Neel temperature (T(N)) of the pseudoternary alloys RCu(2-x)Ni(x)Si2 (R = Pr, Gd, and Dy) and R(1-x)La(x)Cu2Si2 (R = Pr and Gd) is reported. There is an increase in rho just below T(N) in several alloys, followed by the usual decrease at lower temperatures due to the loss of spin-disorder contribution. We attribute this rise in rho to the formation of an energy gap at the Fermi surface due to antiferromagnetic ordering.