| We useinfrared and optical spectroscopic tools to determine the transport effective mass and scattering enhancement in Ce115, UGe2, and a number of other materials exhibiting narrow band magnetism. A feature shared between all these materials is the occurance of a mass enhancement at low temperature and low frequency, along with a suppression of the scattering rate. The mass enhancement and reduction of scattering rate are particularly pronounced when the material becomes magnetically ordered. Simultaneous with the renormalisation effects on the low energy charge carriers, low energy interband transitions become visible. This suggests an interesting interplay between the formation of one or several narrow bands out of the local magnetic moments, and the renormalization presumably due to the coupling of charge carriers to magnetic exitations. |
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