Possible double magnetic phase transition in Dy5CuPb3Dy5CuPb3

We have investigated the magnetic and transport properties of Dy5CuPb3Dy5CuPb3 by magnetic susceptibility, electrical resistivity, magnetoresistance and thermoelectric power measurements. The compound crystallises in the hexagonal Hf5CuSn3Hf5CuSn3-type structure (space group P63/mcmP63/mcm) and probably undergoes two successive magnetic transitions at TC=45.0±0.5K and TN=6.5±0.5K. The experimental data are indicative of a ferri- and antiferromagnetic types of the transitions, respectively. We attribute the double magnetic phase transition and the reduction of the magnetisation values at low temperatures to associate with the two non-equivalent magnetic sublattices of the Dy3+Dy3+ ions. We observed a large magnetoresistance value of -24%-24% at temperatures in between TNTN and TCTC. The investigated compound has a negative thermoelectric power of -17μV/K at 300 K. We interpret the overall behaviour of the S(T)S(T)-curve to two different mechanisms: magnetic and charge carrier diffusion.

Temperature dependence of the reciprocal magnetic susceptibility. The dashed line is the fit of the experimental data to the Curie–Weiss law. Inset a shows the low-temperature magnetisation. Inset b shows the product χTχT as a function of temperature.Figure optionsDownload as PowerPoint slide