Specific Heat, Susceptibility and High-Field Magnetisation Experiments on Heavy Fermion UPt3 Alloyed with Pd

Specific heat, susceptibility and high-field magnetisation experiments have been performed on a number of pseudobinary U(Pt1-xPdx)3 compounds with x ≤ 0.30. For low Pd concentrations (x ≤ 0.10) the spin-fluctuation contribution to the specific heat is enhanced with respect to pure UPt3. For x ≥ 0.15 the spin-fluctuation phenomena are lost. On alloying, the anomalies present for UPt3 in the susceptibility at 17 K and in the high-field magnetisation at 21 T (at 4.2 K), shift towards lower temperatures and fields, respectively, and have not been observed in a compound with x = 0.15. Superconductivity has not been found down to 40 mK in a U(Pt0.995Pd0.005)3 sample

Superconducting and Magnetic Transitions in the Heavy-Fermion System URu2Si2

The intermetallic compound URu2Si2 can be classified as a heavy-fermion system because of its large linear specific-heat coefficient γ=180 mJ/mol·K2. Susceptibility, magnetization, and specific-heat measurements on single-crystal samples indicate both a magnetic phase transition at 17.5 K and a superconducting transition at 0.8 K. The magnetic and superconducting properties are highly anisotropic

Disorder-to-order transition in the magnetic and electronic properties of URh_2Ge_2

We present a study of annealing effects on the physical properties of tetragonal single--crystalline URh_2Ge_2. This system, which in as-grown form was recently established as the first metallic 3D random-bond heavy-fermion spin glass, is transformed by an annealing treatment into a long-range antiferromagnetically (AFM) ordered heavy-fermion compound. The transport properties, which in the as-grown material were dominated by the structural disorder, exhibit in the annealed material signs of typical metallic behavior along the crystallographic a axis. From our study URh_2Ge_2 emerges as exemplary material highlighting the role and relevance of structural disorder for the properties of strongly correlated electron systems. We discuss the link between the magnetic and electronic behavior and how they are affected by the structural disorder.Comment: Phys. Rev. B, in print (scheduled 1 Mar 2000