Optical response to orbital and charge ordering in a layered manganite:La1/2Sr3/2MnO4

Abstract
Change of electronic and lattice structures upon the orbital and charge-ordering (OO-CO) transition has been investigated for a single-layer manganite crystal of La1/2Sr3/2MnO4. The optical birefringence signal probes the orbital-ordering-induced anisotropy in the originally tetragonal MnO2 lattice. In the course of the OO-CO transition, the conductivity spectrum shows a significant change over a wide energy region (0–3 eV), forming a prominent peak around 1.3 eV as well as producing activated phonon modes.