RKKY theory

The proportionality constant may be found by fitting the experimental value for Gd. For the other metals the 6p predicted from the scaling relation are compared with experimental values in tablq 3.8. The experimental values are taken from the review by Koehler (1972). In cases where the paramagnetic property is anisotropic, the average 0p is used for comparison. The small discrepancies between the theory and experiment should be viewed as evidence that the electronic structures of these metals are not identical. Applications of the RKKY theory to explain the magnetic behavior of rare-earth intermetallic compounds is discussed in ch. 14, sections 2.1.4 and 2.1.5. 

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... 

Since the 4f electrons are strongly localized and the RT2X2 systems show a metallic type of electric conductivity, the exchange interactions of 4f electrons can be described in terms of the well-known RKKY theory, which postulates the coupling between the moments via conduction electrons. 

Following the RKKY theory, the energy of a spin system with an oscillatory character of ordering is given by ... 

Within the RKKY theory, the polarization of the conduction electrons is also responsible for the long-range indirect coupling between the spins of the lanthanide ions. As shown by Oe Gennes (1962), in terms of molecular field theory, the paramagnetic Curie temperature is proportional to the average interaction of one lanthanide ion with all the other lanthanide ions. 

Coleman, 1999). The dynamical competition between the Kondo and RKKY interactions is analyzed by an extension (Smith and Si, 2000 Chitra and Kotliar, 2000) of the dynamical mean-field theory (see (Georges et al., 1996) and references therein). The resulting momentum-dependent susceptibility has the general form... 

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