Electronic and thermoelectric properties of FeRh Pd-doped alloys: Ab initio study

Abstract

In this work, spin polarized total energy calculations were carried out to investigate the structural, energetic, magnetic and thermoelectric properties of Fe50Rh50-xPdx (x = 1.9, 3.7, 5.6, 6.3, 7.4, 9.3, 12.5, 18.8 and 25.0) and to compare with previous results of two-component undoped alloy. Some electronic characteristics were evaluated computing the local density of orbital states (LDOS). The corresponding magnetic moments per atom as well as thermal and electrical conductivity were obtained to complete the analysis. We have found that in the range of Pd concentrations studied, the cell parameter for the FM phase increases slightly as × increases with increasing cell volume (0.2–1.9%). The structures are B2 type. As × increases the AFM phase is more stable than the FM. Concerning the AFM phase, the tetragonal distortion along the z-axis is accompanied by a slight stabilization of the total energy with respect to the cubic phase. The cell volume of the AFM phase is less than that corresponding to the FM phase (varying ~ 0.4 considering the cubic and ~ 0.9 considering the tetragonal). The transition temperature was estimated and the trend agrees with the experimental evidence that the increase of Pd content shifts the transition temperature at lower temperatures. From the DOS (EF) we have also estimated the entropy change (ΔSe) obtaining values ranging from 1 to 9 J/molK depending on the Pd content. Another consequence of the magnetic transition is the drop of the resistivity (ρ) in the FM phase compared to the AFM state in the studied range from 100 K to 300 K. These results agree with literature experimental data.