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1

The Effect of Ce Dilution on the Ferromagnetic Ordering in CeAuGe

100%

Sondezi B., Strydom A.

Acta Physica Polonica A

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2015

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vol. 127

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issue 2

228-230

EN

Transport and thermodynamic properties of the well-ordered hexagonal CeAuGe compound have been studied. This compound is known to order ferromagnetically at T_{C} = 10 K with well-defined anomalies in magnetic susceptibility χ(T), electrical resistivity ρ(T) and specific heat C_p(T) characterising the phase transition. The location of T_{C} has been observed to be unstable and enhanced even in moderate applied magnetic fields. However, the dilution of magnetic species, Ce, with the non-f electron element, La, is shown in this work to achieve a continuous suppression of T_{C} to 0 K. The integrity of the space group and the details of the unit cell occupation are retained throughout the substitution series, as is the high-temperature localized Ce-effective magnetic moment μ_{eff} = 2.54 μ_{B}/(mol Ce). Our studies of physical properties down to 0.05 K show a quantum critical form of non-Fermi liquid behaviour, characterised by a logarithmic divergence in C_p(T)/T data in the very dilute Ce content.

2

Physical Properties Study of the CeOsGa₄ Compound

100%

Sondezi B., Strydom A.

Acta Physica Polonica A

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2018

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vol. 133

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issue 3

398-400

EN

A polycrystalline sample of CeOsGa₄ was prepared by arc-melting stoichiometric quantities of high purity elements of 4N and greater, in an arc furnace. The data was confirmed to crystallize in an orthorhombic structure, with a space group Pmma (Number 51). Measurements of the magnetic susceptibility showed a distinct anomaly around T_{o} = 3.8 K, while the high temperature data (above 100 K) obeys Curie-Weiss law. The calculated effective moment of 2.44 μ_{B}, was obtained, which was a bit less than the theoretical moment for a Ce³⁺ ion of 2.54 μ_{B}. Magnetization data at T=2 K depicts that CeOsGa₄ does not saturate up to applied magnetic field of 7 T, while the data measured at 9 K indicates that the compound is purely paramagnetic at that temperature. The low temperature specific heat data is characterized by an anomaly at T_{o} = 3.8 K confirming the χ(T) data. Electrical resistivity shows a metallic behaviour at high temperatures with a deviation at low temperatures, signalling the cooperative behaviour which results to ordering. In this work we present the initial studies of the physical properties measurements performed on this compound.

3

Magnetic and Thermodynamic Properties of Ce₄RuAl

71%

Debnath J., Strydom A., Sondezi B., Tappe F., Pöttgen R.

Acta Physica Polonica A

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2015

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vol. 127

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issue 2

237-239

EN

The results of magnetic susceptibility and heat capacity measurements are reported for the Ce₄RuAl compound above room temperature to low temperature range (400 K to 0.34 K) and in the magnetic field up to 7 T. The magnetic susceptibility χ(T) exhibits a distinct anomaly at 0.95 K which most probably suggests a paramagnetic to antiferromagnetic phase transition. The magnetic susceptibility obeys the Curie-Weiss law in the region 100-400 K and revealed an effective magnetic moment μ_{eff}=2.18 μ_{B}/Ce which is less than the value for free Ce³⁺ (μ_{eff}=2.54 μ_{B}). The paramagnetic Weiss temperature indicates net antiferromagnetic correlations. In the specific heat a peak at 1.3 K supports the bulk nature of the phase transition observed in χ(T). The Sommerfield coefficient is moderately enhanced in the paramagnetic phase, and suggests f-c correlations among the electrons prior to magnetic ordering. The obtained Sommerfield coefficient γ behavior is consistent with the Anderson model-based theoretical predictions.

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3 Acta Physica Polonica A

1 2018

2 2015

3 Sondezi B.

3 Strydom A.

1 Debnath J.

1 Pöttgen R.

1 Tappe F.

The Effect of Ce Dilution on the Ferromagnetic Ordering in CeAuGe

Physical Properties Study of the CeOsGa₄ Compound

Magnetic and Thermodynamic Properties of Ce₄RuAl