Experimental Evidence: Exchanged Polarons Introducing Ferromagnetic Ordering in Strongly Correlated Electronic Materials of Doped Manganites

We present direct experimental evidence that ferromagnetic (FM) transition in doped manganites is introduced by exchanged polarons rather than `bare' e_g electrons and the FM transition depends on hopping energy of polarons regardless of variation of experimental methods. The observed universal relationships between polaron hopping energy and FM transition suggest a simply polaron exchange picture for understanding the origin of FM ordering in the complex strongly correlated electronic materials of manganites.