Nanoscale phase separation in $La_{0.7}Ca_{0.3}MnO_3$ films: evidence for the texture driven optical anisotropy

TL;DR

This study investigates the optical anisotropy in LaCaMnO3 films, attributing it to texture-driven phase separation and ellipsoidal inclusions, with implications for understanding insulator-metal transitions.

Contribution

It introduces an effective medium model linking optical anisotropy to texture-induced phase separation in LaCaMnO3 films.

Findings

Strong linear dichroism observed in single crystal films

Optical anisotropy explained by ellipsoidal inclusions of quasimetal phase

Temperature dependence of spectral weight indicates insulator-metal transition

Abstract

The IR optical absorption (0.1-1.5 eV) in the $La_{0.7}Ca_{0.3}MnO_3$ films on LAO substrate exhibits the drastic temperature evolution of the spectral weight evidencing the insulator to metal transition. Single crystal films were found to reveal strong linear dichroism with anomalous spectral oscillations and fairly weak temperature dependence. Starting from the concept of phase separation, we develop the effective medium model to account for these effects. The optical anisotropy of the films is attributed to the texturization of the ellipsoidal inclusions of the quasimetal phase caused by a mismatch of the film and substrate and the twin texture of the latter.