The magnetotransport properties of the intermetallic compound GdCu6

Abstract

We have studied the temperature and magnetic field dependence of the electrical resistivity of GdCu6 and have co-related the results with the temperature dependence of heat capacity and magnetization. The magnetoresistance of GdCu6 is found to be positive both in the paramagnetic and antiferromagnetic regimes. Within the antiferromagnetic regime, the magnetoresistance is very high and increases to still higher values both with increasing field and decreasing temperature. In the paramagnetic regime the magnetoresistance continues to exhibit a finite positive value up to temperatures much higher than that corresponding to the antiferromagnetic to paramagnetic phase transition. We have shown through quantitative analysis that both the temperature dependences of resistivity and heat capacity indicate the presence of spin fluctuations within the paramagnetic regime of GdCu6. The field dependence of electrical resistivity indicates that the positive magnetoresistance in the paramagnetic phase is not related to the orbital motion of the conduction electrons in a magnetic field (the Kohler rule). In contrast, our analysis indicates that these spin fluctuations are responsible for the positive magnetoresistance observed within this paramagnetic regime. The nature of the field dependence of electrical resistivity is found to be qualitatively similar both in the antiferromagnetic and paramagnetic regimes, which probably indicates that spin fluctuations in the paramagnetic regime are of the antiferromagnetic type.