9-13 July 2012
Africa/Johannesburg timezone
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The magnetocaloric effect in PrNiSi2

Presented by Mr. JL SNYMAN on 12 Jul 2012 from 11:40 to 12:00
Type: Oral Presentation
Session: DCMPM2
Track: Track A - Division for Condensed Matter Physics and Materials


The magnetocaloric effect (MCE) in lanthanide based compounds has attracted sustained interest ever since the discovery of the so called 'giant' MCE in Gd<sub>5</sub>Si<sub>2</sub>Ge<sub>2</sub> by Pecharsky and Gshneidner [1]. Apart from its applicability in new energy efficient refrigeration technologies, the MCE is also a useful probe into the magnetic properties of a system. Recent research focuses on the interplay between the MCE and the salient features of <i>4f</i>-electron magnetism [2]. In this regard PrNiSi<sub>2</sub> offers an interesting case study. The system orders ferromagnetically below 20K [3,4] contrary to the non-magnetic ground state expected for Pr-ions in a crystalline electric field (CEF) with orthorhombic symmetry [5]. Subsequently a study of the MCE in polycrystalline PrNiSi<sub>2</sub> is presented. An anomalous contribution to the MCE is found above the magnetic phase transition temperature. An explanation of the latter in terms of a strong uniaxial anisotropy resulting from leading terms in the CEF Hamiltonian is forwarded. [1] V.K. Pecharsky and K.A. Gshneidner, Jr., Physical Review Letters <b>78</b> (1997) 4494 [2] N.A. de Oliveira and P.J. von Ranke, Physics Reports <b>489</b> (2010) 89 [3] P. Shobinger-Papamantellos and K.H.J. Buschow, Journal of Alloys and Compounds <b>185</b> (1992) 51 [4] A. Gil et al., Journal of Magnetism and Magnetic Materials <b>129</b> (1994) 271 [5] P. Javorsky et al., Journal of Magnetism and Magnetic Materials <b>186</b> (1999) 373






Prof. A.M. Strydom amstrydom@uj.ac.za University of Johannesburg



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