Stress deformations and structural quenching in Sm0.5Ca0.5MnO3 thin films allow a huge decrease of the charge order melting magnetic field

TL;DR

This study investigates how substrate-induced stress and structural quenching in Sm0.5Ca0.5MnO3 thin films significantly lower the magnetic field needed to melt the charge order state, revealing new insights into phase stability.

Contribution

It demonstrates that substrate-induced structural modifications and quenching effects drastically reduce the charge order melting magnetic field in thin films compared to bulk material.

Findings

Structural modifications depend on substrate and film thickness.

Charge order melting magnetic field is significantly reduced in thin films.

Lattice parameters remain unchanged with temperature decrease.

Abstract

Thin films of Sm0.5Ca0.5MnO3 manganites with charge ordering (CO) properties and colossal magnetoresistance were synthesized by pulsed laser deposition technique on (100)-SrTiO3 and (100)-LaAlO3 substrates. We first compare the structural modifications as function of the substrate and film thickness. Secondly, measuring transport properties in magnetic fields up to 24T, we establish the temperature-field phase diagram describing the stability of the CO state and compare it to bulk material. We show that some structural modification induced by the substrate occurs and that the CO melting magnetic field is greatly reduced. Moreover, with the temperature decrease, no modification of the lattice parameters is observed. We then propose an explanation based on the quenching of the unit cell of the film that adopts the in-plane lattice parameters of the substrate and thus, prevents the complete growth of the CO state at low temperature.