ISSN:
1573-7357
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract Anderson's scaling idea is applied to localized paramagnons in the intermediate coupling region. The technique takes as its starting point the Wang-Evenson-Schrieffer functional integral formulation of the Anderson model. It then proceeds by integrating out the effects of the highest frequency random fields in the functional integral, assuming that the motion of these modes may be treated perturbationally relative to that of the lower frequency modes. The remaining problem is then (in lowest approximation) like the original one, except that the effective coupling is smaller. Iterating this procedure, eliminating successively lower and lower frequency random fields, we obtain a differential equation (“scaling law”) for the quadratic coefficient in the functional integral. The solution of this equation leads to an expression for the free energy similar (but not identical) to that obtained in the quartic approximation of Schrieffer, Evenson, and Wang. In a higher order approximation, we find scaling laws for the quadratic and quartic coefficients in the functional integral. These cannot be solved analytically, but they enable one to see qualitatively the effect of the sixth-order terms (three-paramagnon forces).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00629568
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