RKKY interaction applications

An ESR study of the concentration dependence of the fully narrowed resonance linewidth in the hexaborides M jEui cB6 (M=Sr or La) in a wide concentration range 0exchange between Eu -ions is due to the presence of free carriers (indirect exchange via the RKKY-interaction), although a straightforward application of the RKKY-theory gives only qualitative agreement with the experimentally observed AH x) curves. In the lanthanum compoimds, the concentration dependence of... 

For a lattice of nearly localized Ce or U impurities in which / is small, the application of pressure should enhance RKKY interactions and consequently 7 n. However, for sufficiently high pressure, or equivalently large l l, Kondo compensation of the local moments should dominate RKKY interactions and suppress the development of long-range magnetic order. This intuitive conclusion, which follows simply from considering that 7 n depends geometrically on y whereas 7 k varies exponentially, is supported... 

In our opinion, the model presented in Section E.3.3 allows a first explanation of all the results obtained with various techniques. However, the model is simple and cannot cover exactly the complex properties determined by the interparticle interactions. For other kinds of interactions, like RKKY interactions present in metallic samples or superexchange interactions which could occur in insulating samples, we think that the model is applicable after some adjustments, on condition that the temperature is sufficiently high for preventing the appearance of a collective state. In fact, the model is basically independent of the kind of interactions. For a disordered assembly of particles with volume dis-... 

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