12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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Intermediate valence and antiferromagnetic Kondo lattice behaviour in Ce(Au1-xNix)2Si2.

Presented by Prof. Moise Bertin TCHOULA TCHOKONTE on 14 Jul 2011 from 13:45 to 14:00
Type: Oral Presentation
Session: CMPMS1
Track: Track A - Condensed Matter Physics and Material Science


<p>The transition from intermediate valence (IV) behaviour in CeNi<sub>2</sub>Si<sub>2</sub> to magnetically ordered Kondo lattice behaviour in CeAu<sub>2</sub>Si<sub>2</sub> is investigated through measurements of X-ray diffraction (XRD), electrical resistivity &rho(T), magnetization &sigma(µ<sub></sub>0H) and magnetic susceptibility &chi(T) on the polycrystalline Ce(Au<sub>1-x</sub>Ni<sub>x</sub>)<sub>2</sub>Si<sub>2</sub> (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 µ<sub>eff</sub> close to that expected for the free Ce<sup>3+</sup>-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(µ<sub>0</sub>H) measurements indicate metamagnetic behavior for alloys in the concentration range 0 ≤ x ≤ 0.1.

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Room: Parthenon

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