Physical properties of polycrystalline Dy₂PdGe₆ and La₂PdGe₆

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• 作者：R. Wawryk^a ; ^{R.Wawryk@int.pan.wroc.pl} ; R. Troć ; ^a ; A.V. Gribanov^b
• 关键词：Rare earth compound ; Magnetic properties ; Electrical transport ; Specific heat ; Thermoelectric power
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：15 April, 2012
• 卷：520
• 期：Complete
• 页码：255-261
• 文件大小：1099 K

摘要

Polycrystalline samples of the intermetallic compounds Dy₂PdGe₆ and La₂PdGe₆ which crystallize in the orthorhombic structure (Cmca space group) were studied by means of magnetic, electrical resistivity, specific heat and differential thermoelectric power measurements. The Dy-germanide is an antiferromagnet below 25(1) K and at low temperature and above magnetic fields of 3.5 T it exhibits a metamagnetic behaviour. Especially the specific heat measurements point to well-localized 4f-electrons in this compound. Whereas the isostructural La-germanide is a nonmagnetic material taken here as a reference compound. A good overall fit of the resistivity to a general Bloch-Gr眉neisen formula indicates its metallic character in contrast to the Dy-germanide being a semimetallic-like conductor. For the latter compound in its ordered state the electrical resistvity, specific heat and thermoelectric power are dominated by electron-magnon scattering with antiferromagnetic spin-wave spectrum typical of anisotropic antiferromagnetic systems. The observed Schottky anomaly yields an assumed crystal field scheme of low-energy lying levels. Its thermoelectric power behaviour achieves medium positive values at high temperatures, indicating a hole domination in electrical transport properties. On the other hand, S(T) below T_N for Dy- and in the whole temperatures measured for La-based compounds is negative, pointing to their electron carrier origin.