Temperature dependence of RKKY interaction

Abstract

One of the motivations for the work was the observation of phase transition in copper phthalocyanine iodine (Cu(pc)I) by Ogawa. In (Cu(pc)I), phase transition at 8K is believed to be due to the indirect exchange interaction. In this study, temperature dependent behavior of the RKKY interaction has been investigated. For the derivation of temperature dependence, the application of the Sommerfeld expansion and new approximation are compared. As the result of calculation the former turns out to be unrealistic. Thus in the latter i.e. the cubic and the quintic approximation, temperature dependence of the RKKY interaction is investigated by numerical methods. We fit the envelope of this interaction to the form of $e^{\alpha\gamma} / $r^\beta$ which depends on distnace and temperature. Both $\alpha$ and $\beta$ for two approximation are compared with those for the original Fermi distribution.