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AM: Magnetismus

AM 13: Postersitzung: Dünne Schichten (1–22), Magnetowiderstand (23–40), Phasenübergänge (41–55), Mikromagnetismus (56–68), Spektroskopie (69–77), Nanokristalline Materialien (78–82), Anisotropie (83–86), Schmelzen (87–90), Weitere Bereiche (91–100)

AM 13.50: Poster

Dienstag, 28. März 2000, 16:00–20:00, A

Magnetism in NpCo₂ — •W. Kopmann¹, W. Wagener¹, M. Hillberg¹, H.-H. Klauß¹, F.J. Litterst¹, E. Schreier², F.J. Burghart², G.M. Kalvius², J. Rebizant³, and G.H. Lander³ — ¹imnf, Technische Universität Braunschweig, D-38106 Braunschweig, Germany — ²Physik-Department, TU München, D-85747 Garching, Germany — ³European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany

The electronic ground state of the actinide Laves phase NpCo₂ has been examined in the past with several methods.

Mössbauer experiments show a broad magnetic spectra below an ordering temperature of 13 K. Magnetisation and magnetic susceptibility measurements show the development of long-range order of antiferromagnetic type below ∼13 K. In contrast neutron diffraction measurments were not able to detect any sign of magnetic long-range order. For the broad Mössbauer spectra two interpretations have been discussed. One explained the broad lineshapes with magnetic fluctuation effects, the other assumes a hyperfine-field distribution.

We performed muon spin relaxation (µSR) measurements at thr Paul-Scherrer-Instutut (CH). We observed a spontaneous muon spin rotation signal below ∼15 K. This clearly proves the formation of a magnetic ordered phase. The signal is damped strongly. The origin of this could be a broad hyperfine-field distribution.