Editing Kondo effect (section)

{{short description|Physical phenomenon due to impurities}}
[[Image:Classickondo.png|thumb|320px|Kondo effect: How gold with a small amount of what were probably iron impurities behaves at low temperatures]]
[[File:Jun Kondo.jpg|200px|thumb|[[Jun Kondo]]]]
In [[physics]], the '''Kondo effect''' describes the scattering of [[conduction electrons]] in a metal due to [[Magnetic impurity|magnetic impurities]], resulting in a characteristic change i.e. a minimum in [[electrical resistivity]] with temperature.<ref>{{Cite journal |first=Alex C |last=Hewson |author2=Jun Kondo  |date=2009 |title=Kondo effect |journal=Scholarpedia |volume=4 |number=3 |page=7529 |doi=10.4249/scholarpedia.7529 |bibcode=2009SchpJ...4.7529H |author2-link=Jun Kondo |doi-access=free }}</ref>
The cause of the effect was first explained by [[Jun Kondo]], who applied third-order [[perturbation theory]] to the problem to account for scattering of [[Atomic orbital|s-orbital]] conduction electrons off d-orbital electrons localized at impurities ([[Kondo model]]). Kondo's calculation predicted that the scattering rate and the resulting part of the resistivity should increase logarithmically as the temperature approaches 0 K.<ref>{{cite journal|doi=10.1143/PTP.32.37|title=Resistance Minimum in Dilute Magnetic Alloys|date=1964|last1=Kondo|first1=Jun|journal=Progress of Theoretical Physics|volume=32|issue=1|pages=37–49|bibcode = 1964PThPh..32...37K |doi-access=free}}</ref> Extended to a lattice of ''magnetic impurities'', the Kondo effect likely explains the formation of [[heavy fermion|''heavy fermions'']] and [[Kondo insulator|''Kondo insulators'']] in intermetallic compounds, especially those involving rare earth elements such as [[cerium]], [[praseodymium]], and [[ytterbium]], and actinide elements such as [[uranium]]. The Kondo effect has also been observed in [[quantum dot]] systems.