Pseudogap and charge ordering in a large-bandwidth electron-doped manganite

Abstract

We study the origin of complex phase transitions in an electron-doped manganite, La_0.2Sr_0.8MnO₃, using high-resolution photoemission spectroscopy and transmission electron microscopy. The results reveal evidence of phase coexistence and charge ordering in an intermediate temperature range unexpected in this high bandwidth system. The charge ordering nucleates above the phase transition temperature of 265 K, indicating a precursor effect. The high-resolution photoemission spectra exhibit unusual chemical potential shift and persistence of quasiparticles within the insulating phase below 265 K, where the charge-ordered phase dominates and hysteresis is observed in the resistivity. These results provide insight in the study of correlated electron systems exhibiting complex behaviors.