Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.20: Poster

Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B

Magnetic order of CeNi_xGa_4−x — •Veronika Fritsch¹ and Hilbert v. Löhneysen^1,2 — ¹Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany — ²Institut für Festkörperphysik, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany

We investigate the ternary Ce-Ni-Ga system with samples prepared by flux-growth method in Ga-flux. The series CeNi_xGa_1−x crystallizes in the tetragonal BaAl₄-structure. The homogeneity range of this structure is restricted to a narrow region around x = 1. The Ga-rich compounds have previously been reported to exhibit ferromagnetism [1]. Our systematic study shows that with increasing Ni content the lattice parameters shrink. However, they do not obey Vegard’s law. The magnetic transition temperature, as identified from the sharp maximum in the magnetic susceptibility, increases slightly with increasing Ni content. On the other hand the absolute value of the magnetization at the transition drops around one order of magnitude. We did not find any difference between field-cooled and zero-field cooled magnetization measurements nor a hysteresis in the magnetization versus field curves. This leads us to the conclusion that our samples order antiferromagnetically.

[1] E. V. Sampathkumaran et al., Phys. Rev. B 47(13), 8349, (1993).