Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.15: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Inelastic Neutron Scattering on the Antiferromagnetic Half-Heusler Alloy CeBiPt — •Gernot Goll1, Oliver Stockert2, Tobias Unruh3, Peter Link3, K. Shigetoh4, and T. Takabatake4 — 1Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe — 2Max-Planck-Institut CPfS, 01187 Dresden — 3ZWE FRM-II, Technische Universität München, 85747 Garching — 4Hiroshima University, Higashi-Hiroshima, Japan
CeBiPt is a semimetal with a rather low charge carrier concentration n=7.7· 1017 cm−3. Below TN ≈ 1 K antiferromagnetic order occurres as evidenced by sharp maxima in the thermodynamic properties. Neutron diffraction experiments have revealed an AF-type I structure with a propagation vector τ = (1 0 0) and moments also along [1 0 0]. The ordered moment µ ≈ 0.6 µB is much lower than the effective moment determined from the Curie-Weiss behavior of the susceptibility at higher T. Crystal-electric field (CEF) splitting of the Ce3+ level might be one origin of a lowered ordered moment. We performed inelastic neutron scattering experiments on TOFTOF at the FRM-II with energy of the incident neutrons Ei=2.7, 5.7, and 16.9 meV and on PANDA with Ei=5.6 meV at 2.8<T<50 K. We found only one CEF excitation at ℏω ≈ 9.5 meV at T = 2 K in line with previous measurements on SV29 at FRJ-2 with fixed Ei=30 meV. This excitation has been identified with the transition between a Γ7 doublet and a Γ8 quartet state. No further inelastic excitations have been observed except for a quasielastic contribution which increases in width with increasing temperature.