Variation of charge/orbital ordering in layered manganites Pr1-xCa1+xMnO4 investigated by transmission electron microscopy

TL;DR

This study systematically investigates how charge and orbital ordering in layered manganites Pr1-xCa1+xMnO4 varies with doping and temperature using transmission electron microscopy, revealing asymmetric behavior and phase crossovers.

Contribution

It provides new insights into the doping-dependent behavior and temperature-induced phase transitions of charge/orbital ordering in layered manganites.

Findings

Modulation wavenumber decreases linearly with x in over-doped crystals.

Incommensurate-commensurate crossover occurs between 0.35 < x < 0.5 and at x=0.65.

Correlation length of CO/OO shortens at x=0.3.

Abstract

Structural features of the charge/orbital ordering (CO/OO) in single-layered manganites Pr1-xCa1+xMnO4 have been investigated systematically by transmission electron microscopy. Analyses of electron diffraction patterns as well as dark-field images have revealed that the CO/OO shows a striking asymmetric behavior as the hole doping x deviates from x = 0.5. The modulation wavenumber linearly decreases with increasing x in the over-hole-doped (x > 0.5) crystals, while much less dependent on x in the under-hole-doped (x < 0.5) crystals. A temperature-induced incommensurate-commensurate crossover is observed in 0.35 < x < 0.5 and x = 0.65. The correlation length of CO/OO in x = 0.3 was proven to become shorter than that in x > 0.3.