Magnetic and transport properties of PrRhSi3
We have investigated the magnetic and transport properties of a noncentrosymmetric compound PrRhSi3 by dc magnetic susceptibility χ(T), isothermal magnetization M(H), thermoremanent magnetization M(t), specific heat Cp(T), electrical resistivity ρ(T,H) and muon spin relaxation (μSR) measurements. At low fields χ(T) shows two anomalies near 15 and 7 K with an irreversibility between ZFC and FC data below 15 K. In contrast, no anomaly is observed in Cp(T) or ρ(T) data. M(H) data at 2 K exhibit very sharp increase below 0.5 T and a weak hysteresis. M(t) exhibits very slow relaxation, typical for a spin-glass system. Even though the absence of any anomaly in Cp(T) is consistent with the spin-glass type behavior, there is no obvious origin of spin-glass behavior in this structurally well ordered compound. The crystal electric field (CEF) analysis of Cp(T) data indicates a CEF-split singlet ground state lying below a doublet at 81(1) K and a quasi-triplet at 152(2) K. The ρ(T) data indicate a metallic behavior, and ρ(H) exhibits a very high positive magnetoresistance, as high as ∼300% in 9 T at 2 K. No long range magnetic order or spin-glass behavior was detected in a μSR experiment down to 1.2 K.
Crystal structure and thermodynamic properties of NdCu4Au compound
Abstract We report the synthesis of the antiferromagnet cubic-type structure NdCu4Au derived by substituting Au for Cu in the parent binary NdCu5 compound. The room temperature X-ray diffraction analysis indicates a cubic MgCu4Sn-type structure with space group F 4 ¯ 3 m (No. 216) for the NdCu4Au compound. The thermodynamic properties of NdCu4Au have been probed by magnetic susceptibility, χ ( T ) , magnetization, M ( μ 0 H ) , and specific heat, Cp(T), measured down to 1.8 K. The low temperature χ ( T ) data shows probably an antiferromagnetic (AFM)-like anomaly associated with a Neel temperature TN=3.9 K. In the paramagnetic region, χ ( T ) data follows the modified Curie–Weiss law with an effective magnetic moment μ eff = 3.547 ( 5 ) μ B and Weiss temperature θ p = − 10.19 ( 8 ) K . The value for μeff is close to the value of 3.62 μB expected for the Nd3+-ion. No evidence of metamagnetic transition was observed from the isothermal M ( μ 0 H ) results. Cp(T) data confirm the AFM phase transition at TN=3.5 K close to the value of 3.9 K observed in χ ( T ) . The 4f-electron specific heat shows a Schottky-type anomaly around 20 K associated with crystalline-electric-field (CEF), with energy splitting Δ1=62(5) K and Δ2=109(9) K of the Nd3+ (J=9/2) multiplet, that are associated with the first and second excited state of Nd3+-ion. From the results of the 4f-electron magnetic entropy, it is speculated that the CEF ground state of Nd3+ (J=9/2) ions is the Γ6 doublet for NdCu4Au.
Resistivity and magnetoresistance studies on RCoGe3 (R = La, Ce) compounds
Resistivity ( ) and magnetoresistance ( / (0)) have been measured for polycrystalline LaCoGe3 and CeCoGe3 compounds. The temperature dependence of for the La compound is described by T 3 for T << D and T at high temperatures. At 4.5 K a significantly large / (0)(~1) is observed. In CeCoGe3 (T ) exhibits a sharp drop below the magnetic ordering temperature, 21 K. In the antiferromagnetic region between 4 and 16 K it follows a quadratic temperature dependence. The magnetic contribution to resistivity, m , exhibits a maximum at ~125 K above which it decreases following a logarithmic temperature dependence. The magnetoresistance remains positive for temperatures between 4.5 and 30 K but shows field induced transitions at ~7 kOe and ~28 kOe.