Electronic and structural transition in $La_{0.2} Sr_{0.8} Mn O_3$

摘要

We investigate the interplay of the electronic and structural transition inLa$_{0.2}$Sr$_{0.8}$MnO$_{3}$. The transport and specific heat measurementsexhibit unusual evolutions and signature of a first order phase transitionaround 265 K. Mn K-edge extended $x$-ray absorption fine structure resultsreveal distortion in the MnO$_6$ octahedra even in the cubic phase and aremarkable evolution of the distortion across the phase transition. Theseresults manifest the importance of fluctuations in Mn 3$d$ orbital occupancyand disorder in their electronic properties, which may help in understandingthe orbital and spin ordering proposed in these systems.