Abstract
BiFeO3 is one of the most promising multiferroic materials but undergoes two major drawbacks: low dielectric susceptibility and high dielectric loss. Here we report high in-plane dielectric permittivity (ε’ ∼2500) and low dielectric loss (tan δ < 0.01) obtained on Bi0.95Y0.05FeO3 films epitaxially grown on SrTiO3 (001) by pulsed laser deposition. High resolution transmission electron microscopy and geometric phase analysis evidenced nanostripe domains with alternating compressive/tensile strain and slight lattice rotations. Nanoscale mixed phase/domain ensembles are commonly found in different complex materials with giant dielectric/electromechanical (ferroelectric/ relaxors) or magnetoresistance (manganites) response. Our work brings insight into the joined role of chemical pressure and epitaxial strain on the appearance of nanoscale stripe structure which creates conditions for easy reorientation and high dielectric response, and could be of more general relevance for the field of materials science where engineered materials with huge response to external stimuli are a highly priced target.
Highlights
Multiferroics (MF) are materials which have simultaneously more ferroic properties, such as ferroelectric, antiferrodistortive or magnetic order[1]
It has been shown that tetragonal-like BFO films can be grown even on low-mismatch substrates such as STO by controlling the growth rate and deposition temperature[20,21,22,23]
At low growth rates and/or high substrate temperature the incident adatoms can diffuse more and follow the substrate lattice, while at high growth rates or low deposition temperature the arriving adatoms will accumulate in island-type zones where a high strain state is created
Summary
Multiferroics (MF) are materials which have simultaneously more ferroic properties, such as ferroelectric, antiferrodistortive or magnetic order[1]. The multitude of their properties is given by the coupling between the various ferroic orders, which can boost the developing of new multifunctional devices. There are two main ways to control the phase stability and transition temperatures in BFO: one is through strain engineering and the other is through chemical substitutions. Both aim to induce, by different means (mechanical pressure or chemical pressure) a mixed state, characterized by coexisting phases, in order to improve its dielectric and electromechanical response. The two degrees of freedom, polar displacements and oxygen www.nature.com/scientificreports/
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