Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”

TT 24.31: Poster

Mittwoch, 10. März 2004, 14:30–19:00, Poster A

Ferromagnetic to paramagnetic quantum phase transition of single crystal CeSi_1.81 at high pressure — •S. Drotziger¹, C. Pfleiderer¹, M. Uhlarz¹, H. v. Löhneysen^1,2, D. Souptel³, W. Löser³, and G. Behr³ — ¹Physikalisches Institut, Universität Karlsruhe, D-76128 Karlsuhe — ²Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsuhe — ³Institut of Solid State and Materials Research Dresden, Postfach 270116, D-01171 Dresden

Silicon deficient CeSi_2−x crystallizes over a large range of compositions in the orthorhombic α-GdSi₂ structure. Below a critical Si content, easy-plane ferromagnetism is observed. Being one of the rare examples of a ferromagnetic Ce compound, the nature of this ferromagnetic state has been studied intensively in the past. Here we report a high pressure study of the magnetisation of a new generation of CeSi_2−x single crystals grown with an optical floating zone furnace under ultrapure conditions. In CeSi_1.81 where T_C=9.5 K, moderate pressures are sufficient to suppress ferromagnetism. The easy-plane ferromagnetic to paramagnetic quantum phase transition is compared with the predictions of weak-coupling spin fluctuation theory.