RKKY mechanism,

Fig. 2 Schematic diagrams of two representative mechanisms for spin-alignment in conducting magnets, (a) Stoner mechanism, (b) RKKY mechanism...

Figure 6.6 Interaction between magnetic impurities through RKKY mechanism. Interaction between the magnetic impurity at the origin 0 and that at a distance r = 0/4 is antiferromagnetic interaction with a second impurity at r = OB is ferromagnetic. It is seen that the interaction is oscillatory and dies away slowly as the inverse cube of r.

For a low concentration of conduction electrons the wave vector k will be small and the RKKY mechanism will always give ferromagnetic coupling. It then... 

It is widely accepted that the moment coupling in rare earth alloys proceeds by means of the long-range RKKY mechanism involving a spatial non-uniform conduction electron polarization. The coupling constant of eq. (25) then takes the form (De Gennes, 1962a,b) ... 

The Curie temperature in alloys where the RKKY mechanism is the main source of the localized moment coupling, was taken as a convenient experimental quantity reflecting the strength of this conduction electron polarization. In the RKKY approach the conduction electron polarization produced by a given localized rare earth spin is proportional to A second rare earth spin will orient itself... 

By this statement we mean that a-Pr does not order magnetically via the normal RKKY mechanism which governs the other lanthanides. a-Pr does order, however, at 40 mK via a hyperfine interaction between the 4f electrons and the nuclei (Bjerrum-Moiler et al. 1982). 

T. The authors assume for RMni j Sn2 the narrow band formed by the 3d-electron lies close to the Fermi level. Th suggest that magnetism of these compounds preferably arises from weak R—Mn and R—R interactions, i.e. Mn atoms only couple via a RKKY mechanism. 

The incompletely filled 4f-shell confers a magnetic moment to the lanthanide ions and it is the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism via polarization of the conduction electrons which is responsible for the occurrence of long-range ordered magnetic structures in the lanthanide metals. Details can be foimd in numerous reviews, among others in vol. 1, chs. 3, 6 and 7 (1978) of this Handbook series and a recent one by Jensen and Mackintosh (1991). The addition of hydrogen, both in solution or resulting in hydride formation, leads to a decrease of the conduction electron density e (cf. sect. 5)... 

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