Ferromagnetic to paramagnetic quantum phase transition of single crystal CeSi1.81 at high pressure

S. Drotziger1, C. Pfleiderer1, M. Uhlarz1, H. v. Löhneysen1,2, D. Souptel3, W. Löser3 und 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 CeSi2-x crystallizes over a large range of compositions in the orthorhombic a-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 CeSi2-x single crystals grown with an optical floating zone furnace under ultrapure conditions. In CeSi1.81 where TC = 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.