Magnetic and electrical-resistance behavior of the compounds RPt₂Ge₂ (R=rare earth)

Abstract

The results of magnetic-susceptibility, electrical-resistivity (2-300 K), and ¹⁵¹Eu Mössbauer measurements (4.2-300 K) are presented for the series of compounds RPt₂Ge₂ (R=La, Ce, Pr, Eu, and Gd), which have recently been reported to crystallize in a monoclinic variant of the tetragonal CaBe₂Ge₂-type structure. The results clearly establish that CePt₂Ge₂ is an antiferromagnetic Kondo lattice (T_N=2.2 K). GdPt₂Ge₂ appears to order antiferromagnetically below 5 K. Clearly de Gennes scaling of T_N breaks down for CePt₂Ge₂. Eu in EuPt₂Ge₂ is divalent and orders antiferromagnetically at 12 K. There is a contraction of the unit cell in the c direction in this compound, which, we believe, is an indication for strong 4f bonding. There is no clear indication for magnetic ordering in PrPt₂Ge₂ in the temperature range investigated.