Magnetische Ordnung und Kristallfeldeffekte in Cer Deuterid

Abeln, A.

Book/Report

FZJ-2018-02800

Magnetische Ordnung und Kristallfeldeffekte in Cer Deuterid

Abeln, A. (Corresponding author)FZJ*

1987
Kernforschungsanlage Jülich, Verlag Jülich

Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 2152, 106 p. (1987)

Please use a persistent id in citations: http://hdl.handle.net/2128/18418

Report No.: Juel-2152

Abstract: In this work investigations of the magnetic order, crystal field effects and structural transformations in Ce deuteride by measurements of the rnagnetization and susceptibility, specific he gt, neutron scattering, DTA and X-ray diffraction are presented. From this, it follows that both the exchange interaction and the crystal field ground state are strongly affected when the D atoms in the fcc lattice not only occupy the tetrahedral (T) sites but additionally the octahedral (O) sites. Für the lowest concentration of the range of homogeneity, corresponding to D/Ce = 1.95, only the T sites are occupied. This leads to an unsplit ground state, quartet $\Gamma$8. Due to the occupation of the O sites, above D/Ce m 1.95 we observe a splitting of the $\Gamma$7 state into two doublets, indicating a distortion of the cubic lattice, though macroscopically the lattice remains cubic. This Iocal distortion is fully developed at a few percent octahedral D atoms and remains up to full occupation of the O sites, where X-ray investigations Show also a cubic lattice. On the other hand, the excited state, doublet $\Gamma$7, is nearly independent of the D concentration and is Iocated at about 20 mev above the ground state. Sirnilar to the ground state, also the magnetic order is strongly affected by the octahedral D atoms. From the cornplicated magnetic phase diagram obtained, lt is assurned that the $\textit{octahedral}$ $\textit{D}$ atoms involve a ferromagretic exchange interaction via the conduction electrons. This is confirmed by the observation that for D/Ce > 2.75, where the conduction electrons are frozen out, an antiferromagnetic structure appears which is nearly the saure as in the metallic CeD$_{1.95}$ where the O sites are empty.

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