RKKY-like models

More recently, the many theoretical models proposed for an understanding of GMR effects may be classified into two types of approaches, one based on RKKY (Rudeman-Kittel-Kasuya-Yoshida)-like schemes and the other on energy-band structure calculations. 

The eqs. (lid) and (lie) can thus be generalized, not implying anymore the special distance dependence of the RKKY model [eq. (Ilf)] and allowing the experimental distinction between the influence of 6s-(6p-) and 5d-like conduction electrons to be made ... 

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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