Experimente an der Neutronenquelle des Hahn-Meitner-Instituts, Berlin.

• Unité de recherche: PCRD EU
• Numéro de projet: 96.0436-2

Mots-clé (Anglais)

Neutron scattering; magnetism; super conductivity

Autre Numéro de projet (Anglais)

EU project number: ERBFMGECT950060

Programme de recherche (Anglais)

EU-programme: 4. Frame Research Programme - 10.1 Stimulation of training and mobility

Description succincte (Anglais)

See abstract

Autres indications (Anglais)

Full name of research-institution/enterprise:
Paul Scherrer Institut PSI / ETH Zürich
Labor für Neutronenstreuung

Partenaires et organisations internationales (Anglais)

Hahn-Meitner-Institut, Berlin (BRD), Physik-Institut, TU Graz (A), Institute of Physios, Krasnoyarsk (RU), Institute Laue-Langevin, Grenoble (F)

Résumé des résultats (Abstract) (Anglais)

Within the present project neutron scattering investigations were performed at the Hahn-Meitner-Institute, Berlin. The results can be summarized as follows:
1. Superconductors: (a) Extensive studies of the magnetic excitations of Nd ions in the high-temperature superconducting compound Nd2-xCexCuO4 (00.10. Qur findings clearly prove that Nd2-xCexCuO4 cannot be considered as a prototype of a novel heavy-fermion system [1], in contrast to various theoretical works. (b) INS experiments were performed for the novel superconductors of type RMxNi2-x11B2C (R=Ho, Er, Tm; M=Co, Cu; 02. Magnetic materials: (a) The dispersion of the magnetic excitations was determined for the spinel-type ferrimagnet CuFe2O4 (Tc=750 K) in the temperature range 300 k < T < 750 K. Two non-degenerate spin-wave branches were observed which are separated by about 30 meV at room temperature. Upon increasing the temperature, the splitting decreases and disappears at 680 k, while the lower spinwave branch persists up to T. Further critical scattering experiments are planned to investigate this unusual behaviour. (b) LiCu2O2 is a novel mixed-valent spin-ladder compound with alternating Cu and Li chains. Magnetic susceptibility measurements show a broad maximum at 23 K which was interpreted as a transition to a 3-dimensionally ordered magnetic state. Our neutron diffraction experiments, however, gave no evidence for a magnetic phase transition (probably due to the small size of the ordered Cu moment).
[1] W. Henggeler et al., Phys. Rev. Lett. 80,1300 (1998).

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 96.0436-2