Magnetic and transport properties in the low-carrier system Gd1-xLuxInCu4

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Abstract
GdInCu4, which forms the cubic C15b-type crystal structure, is ordered antiferromagnetically at a very low temperature of 6.9 K in spite of the large antiferromagnetic correlation expected from the large negative paramagnetic Curie temperature, -45 K. The electrical resistivity shows anomalous temperature dependence, that is, with increasing temperature, the resistivity reaches a maximum at about 80 K and decreases monotonically at higher temperatures. To study the magnetic and transport properties of GdInCu4 in more detail, we measured systematically the magnetic susceptibility, electrical resistivity and thermal expansion of the Gd1-xLuxInCu4 system. The AC susceptibility and Hall coefficient of GdInCu4 were also measured. The results indicate that Gd1-xLuxInCu4 is a low-carrier system and that the variation of carrier concentration caused by the change of unit cell volume and temperature affects sensitively both transport and magnetic properties. An analysis of specific heat and AC susceptibility suggests that an antiferromagnetic short-range magnetic correlation in GdInCu4 persists at temperatures higher than TN. The concept of magnetic frustration is applied to explain the anomalous magnetic properties.