Small polarons as charge carriers in the transport of (La1/3Sm2/3)0.67Ba0.33−xSrxMnO3 (x=0, 0.1, 0.2 and 0.33)

It is shown that charge transport in substituted manganites (La1/3Sm2/3)0.67Ba0.33−xSrxMnO3 (x=0.0, 0.1, 0.2 and 0.33) is through polarons which are formed through electron-phonon interaction whose strength determines the mobility of the charge carrier. For weak coupling, the free phonon mode is only slightly affected but in strong coupling, the free phonon mode disappears and 'displaced' phonon modes appear. This is seen directly in IR spectra.