Fermi Liquid Theory and Ferromagnetic Manganites at Low Temperatures

Fermi liquid characteristics for ferromagnetic ~manganites, A$_{1-x}$B$_x$MnO$_3$, are evaluated in the tight-binding approximation and compared with experimental data for the best studied region $x\simeq0.3$. The bandwidths change only slightly for different compositions. The Sommerfeld coefficient, $\gamma$, the $T^2$-term in resistivity and main scales in optical conductivity agree well with the two band model. The ``2.5'' - transition due to a ``neck'' forming at Fermi surface, is found at $x=0.3$. The mean free path may change from 3 to 80 interatomic distances in the materials, indicating that samples' quality remains a pressing issue for the better understanding of manganites.