Electronic and structural transition in La_0.2Sr_0.8MnO₃

Abstract

We investigate the interplay between the electronic and structural transitions in La_0.2Sr_0.8MnO₃. The transport and specific heat measurements exhibit unusual evolution and the signature of a first order phase transition at around 265 K. Mn K-edge extended X-ray absorption fine structure (EXAFS) results reveal distortion in the MnO₆ octahedrons, even in the cubic phase, and a remarkable evolution of the distortion across the phase transition. These results manifest the importance of fluctuations in Mn 3d orbital occupancy on their electronic properties, which may help in understanding the orbital and spin ordering proposed in these systems.