Magnetic cerium compounds

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For the ethylsulphates, with only four independent terms, the equivalent crystal-field operators were derived by Elliott and Stevens (1952) and used by them to interpret the magnetic resonance results (Elliott and Stevens 1953). Only minor modifications of the numerical coefficients of the terms were needed to give a reasonable fit for each member of the series. Some further interactions are required, however, for two cerium compounds. In the hexagonal crystal field of the ethylsulphate, the energy levels of the ground manifold J = f are split into three... 

Structural transition has a drastic effect on the electrical behavior of these indides (abrupt change in the slope), but no observable effect on the magnetic data (table 20). The samarium and ytterbium compoimd show non-Ciuie-Weiss behavior. Specific heat data revealed a high y coefficient of 130 mJ/molK for the cerium compound (Pleger et al., 1987). 

The properties of the solid solution Ce i Lajc Cus In have been compared to the pure cerium compound which exhibits Kondo lattice properties with a specific heat coefficient y = 200 mJ/molK (Tchoula Tchokonte et al., 2003). Susceptibility measurements gave no hint for magnetic ordering in the Cei xLa cCu5ln indides. Resistivity data enabled the extraction of the Kondo temperature for the different compositions. 

Eriksson et al. (1991b) treated the fee (100) surface of a-Ce in the paramagnetic state and included the 4f states in the conduction bands. The calculation used a film (five-layer slab) linearized muffin tin orbitals method (Fernando et al. 1986, Ma et al. 1986). From the results they concluded a magnetic instability for the surface layer. Based upon earlier experiences of such Ce instabilities, they suggested that the surface layer of a-Ce should be y-like. This prediction was subsequently verified by Weschke et al. (1991) by means of photoelectron spectroscopy experiments. This demonstrates that surface properties can be radically different from those of the bulk. The same type of surface effect has also been seen for a-like cerium compounds, Celrj, CePdj ad CeRhj (Laubschat et al. 1990), where again the Ce surface atoms show y-like behaviour. This means that some photoelectron spectroscopy data for a-like Ce systems should be reanalyzed before spectra representing the bulk can be obtained. Calculations by Eriksson et al. (unpublished), where both spin and orbital polarization are allowed for, explicitly show the y-like property of the surface layer. 

Solid solutions can be found also for the cerium compounds, and Rossat-Mignod et al. (1985) have discussed the system CeSbi Te. A small amount off Te doping has a pronounced effect on the magnetism of CeSb. By 4% doping the complex ordering found in CeSb gives way to simple type I order and at higher concentra-... 

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