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TT: Fachverband Tiefe Temperaturen

TT 39: Correlated Electrons: Heavy Fermions 1

TT 39.5: Vortrag

Donnerstag, 26. März 2009, 10:45–11:00, HSZ 304

Magnetic Anisotropy in Tetragonal Rare Earth Compounds — •Veronika Fritsch¹, Michael Marz¹, and Hilbert v. Löhneysen^1,2 — ¹Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany — ²Institut für Festkörperphysik, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany

We have investigated single crystals of RAu₂Ge₂ with R = Ce and Pr as well as Ce₂MGa₁₂ with M = Ni, Pd and Pt, grown by a flux growth method with Au-Ge flux for RAu₂Ge₂ and Ga flux for Ce₂MGa₁₂. The latter crystallizes in a tetragonal structure with layers of Ce atoms separated by segments of Ga only alternating with GaPd₆ segments [1]. Measurements of the dc susceptibility χ revealed a strong magnetic anisotropy. For the magnetic field along the c-axis, antiferromagnetic order sets in at 9.6 K (Ni), 10.6 K (Pd) and 5.7 K (Pt), as evidenced by sharp maxima in χ (T), for the magnetic field perpendicular to the c-axis χ (T) continues to increase monotonically down to 2 K. In RAu₂Ge₂ compounds, crystallizing in the considerably simpler ThCr₂Si₂ structure [2], a similar situation was found: with the magnetic field parallel to the c-axis antiferromagnetic order was found at 11.9 K (Ce) and 10.8 K (Pr), but with the magnetic field aligned perpendicular to the c-axis, no evidence for magnetic order is found down to 2 K. We will present measurements of magnetization and electrical resistivity exploring the possible proximity of these systems to a field-induced quantum critical point.

[1] R. T. Macaluso et al., J. Sol. State Chem. 178 (2005) 3547.

[2] A. Loidl et al., Phys. Rev. B 46 (1992) 9341.