Effect of ferroelectric layers on the magnetocapacitance properties of superlattices-based oxide multiferroics

TL;DR

This study investigates how ferroelectric layers influence the magnetocapacitance and multiferroic properties of oxide superlattices, revealing temperature-dependent ferroelectricity, ferromagnetism, and maximum negative magnetocapacitance near transition temperatures.

Contribution

It demonstrates the impact of ferroelectric layer composition on magnetocapacitance and multiferroic behavior in oxide superlattices, highlighting strain effects and temperature dependence.

Findings

Maximum negative magnetocapacitance of 3% per tesla near ferroelectric transition temperature.

Ferromagnetic Curie temperature range of 145-158 K.

Ferroelectricity observed between 55 K and 105 K depending on barium content.

Abstract

A series of superlattices composed of ferromagnetic La$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO) and ferroelectric/paraelectric Ba$_{1-x}$Sr$_x$TiO$_3$ (0$\leq $x$\leq $1) were deposited on SrTiO$_3$ substrates using the pulsed laser deposition. Films of epitaxial nature comprised of spherical mounds having uniform size are obtained. Magnetotransport properties of the films reveal a ferromagnetic Curie temperature in the range of 145-158 K and negative magnetoresistance as high as 30%, depending on the type of ferroelectric layers employed for their growth (\QTR{it}{i.e.} '\QTR{it}{x'} value). Ferroelectricity at temperatures ranging from 55 K to 105 K is also observed, depending on the barium content. More importantly, the multiferroic nature of the film is determined by the appearance of negative magnetocapacitance, which was found to be maximum around the ferroelectric transition temperature (3% per \QTR{it}{tesla}). These results are understood based on the role of the ferroelectric/paraelectric layers and strains in inducing the multiferroism.