Simple Self-Consistent Treatment of Kondo's Effect in Dilute Alloys

概要

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The self-consistent treatment of Kondo's effect by Nagaoka is revised by using the method of Gor'kov in the theory of superconductivity. Expressing the spin operators in terms of Fermi operators, such as s_Z=(a_<↑^+>a_↑-a_<↓^+>a_↓)/2, the Green's functions of the type <<ck'_↑S_Z|ck_↑>> are decomposed into the sum of terms like <a_<↑^+>ck'_↑><<a_↑|ck_<↑^+>>>. The existence of these terms implies the existence of the bound state between the localized spin and the spin density of conduction electrons. Essentially the same expression for the Green's function of conduction electrons as in Nagaoka's treatment is obtained, but we also have the bound state in the case of ferromagnetic coupling. Magnetic susceptibility is calculated in our approximation and is shown to be finite at T=0 and increase with the increasing temperature tending to infinity like (T_c-T)^<-1> as T→T_c.
理論物理学刊行会の論文
1966-03-25