Aiman Kamal Bashir

Magnetic and thermodynamic properties of GdCu4Au

The results of magnetic susceptibility, χ(T), magnetization, σ(μ0H), and specific heat, CP(T), for GdCu4Au are presented. The room temperature powder X-ray diffraction studies indicate a cubic MgCu4Sn – type crystal structure with space group F3m (No.216). The low field dc χ(T) data shows an antiferromagnetic – like (AFM) anomaly associated with a Neel temperature TN = 10.8 K for GdCu4Au. In the paramagnetic region above TN, χ(T) data follows the Curies – Weiss law with an effective magnetic moment μeff = 7.444(1) μB and paramagnetic Weiss temperature θP = -15.01(2) K. The experimental value of is close to the calculated value of 7.94 μB expected for the free Gd3+-ion. The field-cooled (FC) and zero-field-cooled (ZFC) χ(T) data provide evidence for the formation of spin-glass state with a freezing temperature Tf = 15 K. σ(μ0H) measured in the ordering region (below TN) shows that GdCu4Au undergoes metamagnetic transition above 0.7 T, characterized by a slight upward curvature above this field. Measurement of σ(μ0H) in the paramagnetic regions show a linear behaviour up to 0.7 T and a downward curvature at high fields. CP(T) data shows an AFM – like phase transition at TN = 10.4 K close to the phase transition observed in χ(T) results. The 4f-electron entropy reaches the value of Rln2 close to TN at 9.02 K and reaches the value of Rln(2J + 1) at T = 180 K.

Antiferromagnetic ordering in NdAuGe compound

The compound NdAuGe was investigated by means of electrical resistivity, ρ(T), magnetic susceptibility, χ(T), magnetization, σ(μ0H), and specific heat, Cp(T), measurements. Powder X-ray diffraction studies confirm a hexagonal LiGaGe-type structure with space group P63mc (No. 186). ρ(T) data show normal metallic behaviour and a tendency toward saturation at higher temperatures. The low temperature ρ(T) data indicate a phase transition around 3.8 K. The low field dc χ(T) data show an antiferromagnetic anomaly associated with a Neel temperature at TN = 3.7 K close to the phase transition observed in ρ(T) results. At higher temperatures, χ(T) follows the paramagnetic Curie-Weiss behaviour with an effective magnetic moment μeff=3.546(4) μB and a paramagnetic Weiss temperature of θp=−6.1(4) K. The value obtained for μeff is close to the value of 3.62 μB expected for the free Nd3+-ion. σ(μ0H) shows a linear behaviour with applied field up to 3 T with an evidence of metamagnetic behaviour above 3 T. Cp(T) confirm...

Electrical and thermal transport properties of the alloy system (Ce1-xLax)Cu4In

The studies of electrical resistivity, ρ(T), magnetoresistivity, MR, thermoelectric power, S(T) and thermal conductivity, λ(T), of the alloy system (Ce1-xLax)Cu4In (0 ≤ x ≤ 1) are reported. The room temperature powder X-ray diffraction studies confirm the orthorhombic CeCu4.38ln1.62 – type crystal structure with space group Pnnm (No. 58) for all investigated compositions across the series. ρ(T) results indicate an evolution from coherent Kondo scattering to incoherent single – ion Kondo scattering, with increased La content x. ρ(T) for each composition at high temperature is described by a -ln(T) behaviour. MR measurements on Ce dilute alloys are interpreted within the single – ion Bethe ansatz description of the Coqblin – Schrieffer model. S(T) results are described by the phenomenological resonance model. λ(T) data increase linearly with temperature from low T and shows a tendency toward saturation above 300 K for dilute Ce alloys. The Lorentz number, L/L0 and the dimensionless figure of merit, ZT = S2T/λρ increase upon cooling and exhibit maxima at low temperatures.