Anisotropic clusters with itinerant charge carriers in the layered EuBaCo$_{1.9}$O$_{5.36}$ cobaltite

The anisotropy of reflection spectra is studied for the single crystals of layered EuBaCo$_{1.9}$O$_{5.36}$ cobaltite within the temperature range of $80$–$295$ K. The results involving the comparison with the magnetic and transport characteristics are analyzed. In the reflection spectra from the (001) and (120) planes measured at $T=295$ K (below the temperature corresponding to the transition to the semiconducting state, $T_{\mathrm{MI}}=345$ K), a contribution from itinerant charge carriers has been revealed. This contribution is associated with the existence of an inhomogeneous charge state. In the reflection spectrum from the (120) plane, the contribution from itinerant charge carriers holds down to $80$ K. The difference between the reflection spectra from different planes and different characters of their changes with the temperature are attributed to the anisotropy of the clusters with itinerant charge carriers.