Thermoelectric power and electrical resistivity of some Ni-Based alloys near the Curie point

Abstract

The anomalous behaviour of the absolute thermoelectric power (ATP) near the critical point was investigated in Ni and its dilute alloys with some 3d transition elements. Both the ATP and the temperature coefficient of the electrical resistivity (TCER) in the vicinity of the Curie point were measured in Ni(Fe), Ni(Mn) and Ni(Cr) alloys with different impurity concentrations. It was found that the critical behaviour of the transport properties depends strongly on the impurity.

In Ni(Mn) alloys an oscillatory behaviour of the ATP was observed around the Curie point, while there was also a very significant difference in the critical behaviour of the TCER from that in pure Ni, Fe and Cr impurities, on the other hand, did not alter the monotonous temperature dependence of the ATP at the Curie point, and the singularity of the TCER did not differ from that in pure Ni. It is suggested that the peculiar behaviour of Ni(Mn) alloys originates from virtual bound states near the Fermi level, since a shift of the Fermi level at the Curie temperature could drastically change the density of states at the Fermi energy and this might account for the observed anomalies of the transport properties.