12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone

Intermediate valence and antiferromagnetic Kondo lattice behaviour in Ce(Au<sub>1-x</sub>Ni<sub>x</sub>)<sub>2</sub>Si<sub>2</sub>.

14 Jul 2011, 13:45


Oral Presentation Track A - Condensed Matter Physics and Material Science CMPMS1


Prof. Moise Bertin Tchoula Tchokonte (University of the Western Cape)


The transition from intermediate valence (IV) behaviour in CeNi2Si2 to magnetically ordered Kondo lattice behaviour in CeAu2Si2 is investigated through measurements of X-ray diffraction (XRD), electrical resistivity &rho(T), magnetization &sigma(µ0H) and magnetic susceptibility &chi(T) on the polycrystalline Ce(Au1-xNix)2Si2 (0 ≤ x ≤ 1) alloy series. Lattice parameters as derived from XRD measurements deviate from Vegard’s rule around x = 0.6 – 0.8. &rho(T) data indicate Kondo lattice behavior in the presence of a crystal field for x ≤ 0.6, the occurrence of magnetic ordering for x = 0 and fluctuating valency for x ≥ 0.8. &chi(T) data at high temperatures, follow the Curie-Weiss relation for alloys in the concentration 0 ≤ x ≤ 0.6 (Kondo lattice region) and give effective magnetic moment values µeff close to that expected for the free Ce3+-ion. The low temperature &chi(T) data indicate the onset of antiferromagnetic ordering for x ≤ 0.78. For alloys in the concentration range 0.8 ≤ x ≤ 1 (IV region), &chi(T) data are described within the framework of the paramagnon model. &sigma(µ0H) measurements indicate metamagnetic behavior for alloys in the concentration range 0 ≤ x ≤ 0.1.

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Primary author

Prof. Moise Bertin Tchoula Tchokonte (University of the Western Cape)


Prof. Dariuzs Kaczorowski (Polish Academy of Sciences, Poland) Prof. Paul de Villiers du Plessis (University of Johannesburg) Prof. Terry Doyle (iThemba LABS)

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