Strong electron-phonon interaction and colossal magnetoresistance in EuTiO3

摘要

At low temperatures, EuTiO3 system has very large resistivities and exhibits colossal magnetoresistance. Based on a first principle calculation and the dynamical mean-field theory for small polaron we have calculated the transport properties of EuTiO3. It is found that due to electron-phonon interaction the conduction band may form a tiny polaronic subband which is close to the Fermi level. The tiny subband is responsible for the large resistivity. Besides, EuTiO3 is a weak antiferromagnetic material and its magnetization would slightly shift the subband via exchange interaction between conduction electrons and magnetic atoms. Since the subband is close to the Fermi level, a slight shift of its position gives colossal magnetoresistance.