Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.79: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Suppression of magnetic order in YbNiSi_3−xGe_x — •K. Grube¹, W. Knafo¹, C. Meingast¹, S. Drotziger², M. Uhlarz², Th. Wolf¹, P. Adelmann¹, and H. v. Löhneysen^1,2 — ¹Forschungszentrum Karlsruhe, Institut für Festkörperphysik, Germany — ²Physikalisches Institut, Universität Karlsruhe (TH), Germany

YbNiSi₃ shows moderately heavy-fermion behaviour with antiferromagnetic long-range order below T_N = 5.1 K. We have studied the thermodynamic and transport properties of single crystals grown using the flux method with specific heat, DC magnetization, and resistivity measurements in magnetic fields up to 14 T. The magnetic order is suppressed in a magnetic field of 8 T. On the other hand, YbNiGe₃ shows a very small magnetic susceptibility and no sign of magnetic order down to the lowest measured temperature of 1.9 K, indicating an intermediate-valent state. Preliminary experiments on polycrystalline YbNiSi₂Ge samples exhibit signs of magnetic ordering below 3 K. We report on the magnetic phase diagram of YbNiSi₃ and the dependence of the specific heat on the Ge content.