Kondo Effect — Magnetic Impurity Screening

Conduction electrons screen a magnetic impurity → resistance minimum at TK

Parameters

Kondo Effect: A magnetic impurity (e.g. Fe in Au) is antiferromagnetically coupled to conduction electrons. Below TK, a many-body singlet forms — the impurity spin is screened. R(T) = R₀[1 − c·n_i·ln(T/T_K)] + αT⁵ The logarithmic rise in R at low T is the Kondo signature. The resistance minimum occurs where ∂R/∂T = 0.