Strain control of superlattice implies weak charge-lattice coupling in La$_{0.5}$Ca$_{0.5}$MnO$_3$

TL;DR

This study uses electron microscopy to show that in La0.5Ca0.5MnO3, the superlattice structure is weakly coupled to the lattice, indicating minimal charge-lattice interaction and challenging the stripe charge order model.

Contribution

It provides independent evidence from microscopy that manganites lack strong charge-lattice coupling, supporting previous theoretical arguments.

Findings

Superlattice period varies by 2-3% in strain relaxed regions.

Charge-lattice coupling in manganites is weak.

Supports the absence of stripe charge order in manganites.

Abstract

We have recently argued that manganites do not possess stripes of charge order, implying that the electron-lattice coupling is weak [Phys Rev Lett \textbf{94} (2005) 097202]. Here we independently argue the same conclusion based on transmission electron microscopy measurements of a nanopatterned epitaxial film of La$_{0.5}$Ca$_{0.5}$MnO$_3$. In strain relaxed regions, the superlattice period is modified by 2-3% with respect to the parent lattice, suggesting that the two are not strongly tied.