Korringa enhancement factor

In this equation, k is the isotropic Knight shift and Sk is the Korringa enhancement factor, which takes into account the low dimensionality or anisotropy of the conduction as well as electron correlations. Thus, Sk lumps all the complications into one parameter and is given by... 

As shown in Fig. 12, another regime of relaxation is reached at very low temperature (7 <8 K), where a behavior l/T, oc Tis recovered [51, 69, 70, 144]. The low temperature regime looks like a Korringa law with an enhancement factor of the order 10 with respect to the regime r>30 K. It has been first proposed that this change in behavior for the enhancement originates in the dimensionality cross-over of one-particle coherence and the restoration of a Fermi liquid component in two directions. It is still an open problem to decide whether the Fermi liquid properties recovered below 8 K are those of a 2-D or 3-D electron gas. Furthermore the intermediate temperature regime 8 K ... 

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