Antiferromagnetic exchange between a localized magnetic moment and conduction electrons produces strong low-energy correlations and screening of the moment. In a dilute magnetic-impurity metal, a resistance minimum and a low-temperature logarithmic increase are characteristic signatures over an appropriate temperature range. The strong-coupling low-temperature regime cannot be obtained by extending the logarithm indefinitely.
A periodic array of local moments coupled to conduction electrons. Competition between screening, coherent hybridization and intersite magnetic interactions can produce a heavy fermion material, magnetic order or a correlated insulating state.
A Kondo lattice develops coherent low-energy quasiparticle bands below a material-dependent coherence scale. This lattice scale need not equal the single-impurity Kondo screening scale. Coherence can produce a heavy Fermi liquid with narrow bands, large electronic heat capacity and low-temperature quadratic resistivity.
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The Kondo effect is a phenomenon observed in condensed matter physics, specifically in systems that include magnetic impurities within a metal or semiconductor. Named after Japanese physicist Jun Kondo, who first described the effect in 1964, it relates to the behavior of conduction electrons in the presence of localized magnetic moments, such as those caused by impurity atoms.
If you adda bit of impurities to certain materials, at low temperatures of a few Kelvin their resistivity actually starts increasing if you go below a certain critical temperature.
Kondo effect graph for gold with added impurities
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