Specific heat, DC susceptibility, and resistivity measurements on annealed, polycrystalline samples of CeM2Sn2, where M = Ni, Ir, Cu, Rh, Pd, or Pt, indicate that each of these compounds orders antiferromagnetically with transition temperatures ranging from TN = 4.1 to ≈ 0.5 K. All these materials have significant enhancements of the specific heat just before the transition, which can be as large as ∼ 3.5J/mol K2 in some cases. Provided the enhanced heat capacities above TN are associated with large effective masses, the anomalously low ordering temperature and the very large C/T suggest that TN and the Kondo temperature TK are comparable, making these materials particularly attractive for studying the interplay between these competing interactions. The susceptibility for each member of the series except M = Ir follows a Curie-Weiss behavior with a high-temperature effective moment μeff ∼ 2.5μB Ce and a small negative paramagnetic Curie temperature. © 1991.

Specific-heat, magnetic-susceptibility, and resistivity measurements on annealed polycrystalline samples of CeM2Sn2, with M=Ni, Ir, Cu, Rh, Pd, and Pt, indicate that each of these compounds orders antiferromagnetically at Néel temperatures TN between 0.5 and 4.2 K. Just above TN, all these materials have a significant enhancement of their electronic specific heat, which can be as large as 3-4 J/molK2. We discuss the role of critical fluctuations on the specific heat and argue that the enhancement is associated with a large effective mass and not fluctuations. The anomalously low ordering temperatures and very large electronic specific heat suggest that TN and the Kondo temperature TK are comparable, making these materials particularly attractive for studying the competition between Kondo and Ruderman-Kittel- Kasuya-Yosida interactions. Measurements of the pressure dependence of TN in CeIr2Sn2 were performed to explore this competition, which is discussed in terms of Doniach's Kondo-necklace model. © 1991 The American Physical Society.

We have measured specific heat, magnetic susceptibility, and resistivity on the cerium-intermetallic compound CePt2Sn2. The heat capacity shows a strong increase below a few kelvin, typical of a large many-body enhancement of the density of states or equivalently of the effective electronic mass. Just before the material orders antiferromagnetically at TN=0.88 K, the linear temperature coefficient of the specific heat is approximately 3.5 J/mol K2, making this material one of the heaviest electron systems known. The low Néel temperature and huge specific heat imply similarly low-energy scales for competing RKKY and Kondo-like interactions. © 1991 The American Physical Society.