Difference Between Ruderman-Kittel-Kasuya-Yosida (RKKY) Interaction and Kondo Effect The question is in the title. I don't understand the difference between these two effects.
Based on my understanding, the Kondo Effect is where the conduction electrons effectively screen a local magnetic impurity by forming a cloud of opposite polarization around it.
The RKKY interaction seems to be the same thing: conduction electrons form polarized rings around the impurity, effectively screening it.
 A: The RKKY interaction is a generalization of the Kondo calculation in the case of two spins : it deals with finding the correct form of the interaction between two magnetic impurities via the Fermi sea.
In this case you have a competition between two effects : the Kondo that describes the screening of each impurity bu the Fermi sea of electrons, and the RKKY interaction that tunes Ferro or Antiferromagnetic order.
A: This paper should be interesting for you: https://arxiv.org/pdf/0902.0225.pdf, see Figs. 3 and 4.
For a single impurity in a non-interacting bath the spatial dependence of the spin correlation function around the impurity is indeed similar to the Friedel oscillations. The envelope function shows actually power-law and exponential behavior, depending on the length and temperature scale.
The RKKY coupling and the Kondo effect have of course the same origin in the screening of the impurity by the conduction electrons. But I find it difficult to answer the main question, because it is obvious that adding another impurity spin will change the correlations compared to the single impurity case. Let's put the question differently: In what way are the RKKY interaction and the Kondo effect the same? Is it really clear?
