We present the structural, magnetic, thermodynamic, and transport properties of the two new compounds YbPt2Sn and YbPt2In. X-ray powder diffraction shows that they crystallize in different structure types, the hexagonal ZrPt2Al and the cubic Heusler type, respectively. Despite quite different lattice types, both compounds present very similar magnetic properties: a stable trivalent Yb3+, no evidence for a sizeable Kondo interaction, and very weak exchange interactions with a strength below 1K as deduced from specific heat C(T). Broad anomalies in C(T) suggest short range magnetic ordering at about 250mK and 180mK for YbPt2Sn and YbPt2In, respectively. The weak exchange and the low ordering temperature result in a large magnetocaloric effect as deduced from the magnetic field dependence of C(T), making these compounds interesting candidates for magnetic cooling. In addition we found in YbPt2In evidences for a charge density wave transition at about 290K. The occurrence of such transitions within several RET2X compound series (RE = rare earth, T = noble metal, X = In, Sn) is analyzed.
@article{arxiv.1406.6800,
title = {Unusual weak magnetic exchange in two different structure types: YbPt$_2$Sn and YbPt$_2$In},
author = {Thomas Gruner and Dongjin Jang and Alexander Steppke and Manuel Brando and Franz Ritter and Cornelius Krellner and Christoph Geibel},
journal= {arXiv preprint arXiv:1406.6800},
year = {2015}
}