Orbital and Charge Ordering in La1-xSr1+xMnO4(0.4≤x≤0.5)

Abstract

Hole concentration dependence of charge order (CO) and orbital order (OO) in layered perovskite compounds La 1- x Sr 1+ x MnO 4 has been studied by means of the resonant X-ray scattering technique. Both CO and OO are observed below 210 K in the compounds having the hole concentration x between 0.5 and 0.48, but neither is observed for x ≤0.46. The transition temperatures are nearly independent of x between 0.5 and 0.48. Correlation lengths ξ's for both orders obtained from analyses of superlattice peak profiles are finite at any temperature. Moreover, in contrast to the cubic perovskite, ξ for OO is larger than that for CO. ξ for OO is as short as that for CO at the critical concentration of x =0.48. These results suggest that OO is prerequisite to the forming of CO in this system.