Unusual weak magnetic exchange in two different structure types: YbPt${}_2$Sn and YbPt${}_2$In

Abstract

We present the structural, magnetic, thermodynamic, and transport properties of the two new compounds YbPt${}_2$Sn and YbPt${}_2$In. X-ray powder diffraction shows that they crystallize in different structure types, the hexagonal ZrPt${}_2$Al and the cubic Heusler type, respectively. Despite quite different lattice types, both compounds present very similar magnetic properties: a stable trivalent Yb${}^{3+}$, 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 YbPt${}_2$Sn and YbPt${}_2$In, 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 YbPt${}_2$In evidences for a charge density wave transition at about 290K. The occurrence of such transitions within several RET${}_2$X compound series (RE = rare earth, T = noble metal, X = In, Sn) is analyzed.

arXiv comment16 pages, 7 figures

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• Possible Pressure-Induced Charge-Density Wave Quantum Critical Point in LuPd2In