Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 14: Postersitzung III (Neue u. unkonventionelle Supraleiter, Anwendungen der Supraleitung, Dünne Schichten, JJs und SQUIDs, Schwere Fermionen, Kondo-Systeme)

TT 14.42: Poster

Mittwoch, 26. März 2003, 14:30–19:00, P2c

Properties of CeNi_1−xCu_xSn near the onset of magnetic ordering — •R. Vollmer¹, T. Mioković¹, C. Pfleiderer¹, A. Schröder², H. v. Löhneysen^1,3, M. Kalvius⁴, Y. Echizen⁵, and T. Takabatake⁵ — ¹Physikalisches Institut, Universität Karlsuhe, D-76128 Karlsruhe, Germany — ²Department of Physics, Kent State University, Kent OH 44242, USA — ³Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany — ⁴Physics Department, Technical Un. Munich, D-85747 Garching, Germany — ⁵ADSM and MaRCH, Hiroshima University, 2-3-1 Kagamiyama Higashi-Hiroshima, 739-8526 Japan

We report on measurements of the specific heat and the magnetisation of single-crystalline samples of CeNi_1−xCu_xSn (x=0.05, 0.067, and 0.078). The anisotropic pseudogap in the excitation spectrum of CeNiSn is gradually reduced with increasing Cu substitution x, closing completely for x≈ 0.1. On the other hand, magnetic order is observed for x=0.078, a concentration that still shows the energy gap. The specific heat at low temperatures is strongly enhanced, showing non-Fermi liquid (NFL) like behavior for x<x_c, the critical concentration where magnetic order sets in. The scaling behavior of the specific heat with the Cu concentration may suggest that the NFL behavior is of single ion nature although the proximity to a quantum critical point may also be a cause. Neutron scattering data show commensurate and incommensurate contributions to the magnetic ordering. The incommensurate component dominates for x=0.078, i.e., near the critical point where the magnetic order is suppressed, while for x=0.178 the commensurate component dominates.