Tuning the magneto-electrical properties of multiferroic multilayers through interface strain and disorder

TL;DR

This study investigates how interface strain and structural disorder influence the magnetic and electronic properties of ferromagnetic/ferroelectric superlattices, revealing that strain can modulate ferromagnetism and charge localization.

Contribution

It provides systematic insights into the effects of strain and disorder on multiferroic multilayers, highlighting their roles in tuning physical properties.

Findings

Compressive strain decreases ferromagnetism and charge mobility.

Tensile strain increases ferromagnetic transition temperature.

Structural defects mainly impact magnetic properties.

Abstract

Artificially engineered superlattices were designed and fabricated to induce different growth mechanisms and structural characteristics. DC sputtering was used to grow ferromagnetic (La$_{0.8}$Ba$_{0.2}$MnO$_3$) / ferroelectric (Ba$_{0.25}$Sr$_{0.75}$TiO$_3$ or BaTiO$_3$) superlattices. We systematically modified the thickness of the ferromagnetic layer to analyze dimensional and structural effects on the superlattices with different structural characteristics. The crystalline structure was characterized by X-Ray diffraction and transmission electron microscopy. The magnetic and electronic properties were investigated by SQUID magnetometry and resistance measurements. The results show that both strain and structural disorder can significantly affect the physical properties of the systems. Compressive strain tends to increase the competition between the magnetic interactions decreasing the ferromagnetism of the samples and the localization of the charge carrier through the electron-phonon interaction. Tensile strain reduces the charge carrier localization, increasing the ferromagnetic transition temperature. Structural defects have a stronger influence on the magnetic properties than on the transport properties, reducing the ferromagnetic transition temperature while increasing the magnetic hardness of the superlattices. These results help to further understand the role of strain and interface effects in the magnetic and transport properties of manganite based multiferroic systems.