Lamellar phase separation and dynamic competition in La0.23Ca0.77MnO3

TL;DR

This study reveals the coexistence and dynamic competition of lamellar charge-ordered and charge-disordered domains in La0.23Ca0.77MnO3, highlighting temperature-dependent phase evolution and magnetoelastic effects.

Contribution

It provides detailed TEM evidence of lamellar phase separation and its temperature-dependent dynamics in La0.23Ca0.77MnO3, linking magnetic transitions to phase behavior.

Findings

Charge-disordered phase forms below 170K within charge-ordered matrix.

Between 64K and 130K, phases dynamically compete with slow evolution.

Magnetoelastic effects influence the phase dynamics.

Abstract

We report the coexistence of lamellar charge-ordered (CO) and charge-disordered (CD) domains, and their dynamical behavior, in La0.23Ca0.77MnO3. Using high resolution transmission electron microscopy (TEM), we show that below Tcd~170K a CD-monoclinic phase forms within the established CO-orthorhombic matrix. The CD phase has a sheet-like morphology, perpendicular to the q vector of the CO superlattice (a axis of the Pnma structure). For temperatures between 64K and 130K, both the TEM and resistivity experiments show a dynamic competition between the two phases: at constant T, the CD phase slowly advances over the CO one. This slow dynamics appears to be linked to the magnetic transitions occurring in this compound, suggesting important magnetoelastic effects.