Study of Magnetic Interactions in (SnTe–MnTe) and (SnTe–EuTe) Systems

Abstract

As reported earlier the alloy system Sn0.97−x Mn x Te orders ferromagnetically with Curie temperatures varying linearly with x. The present work has extended this and includes: (i) More superconductivity results which indicate that for low carrier densities (∼1021 cm−3), the paramagnetic impurity influences Tc very drastically, e.g., 100‐ppm Mn destroys the superconductivity completely. However, if the carrier density is increased to 4×1021 cm−3, the transition temperature decreases gradually with increasing Mn content and superconductivity persists even for x=0.001. In both cases, however, the transition is broadened probably due the presence of the internal fields. (ii) Electrical resistivitymeasurements made on these samples (0.00001<x<0.10) between 4° and 100°K, show a characteristic metallic behavior but with no maxima or minima appearing in the residual part. (iii) A study of s‐f interactions by means of Eu doping for comparison with s‐d interaction results (Mn doped). Eu‐doped samples are single phase, determined from x‐ray measurements, for x<0.10. Magnetic measurements on the Eu‐doped system have been carried out between 4° and 100°K at a carrier density of ∼1021 cm−3. Superconductivity (down to 0.02°K) measurements have been made in order to complete the comparison between the two systems.