Control of ferroelectricity and magnetism in multi-ferroic BiFeO ₃ by epitaxial strain

Abstract

Recently, strain engineering has been shown to be a powerful and flexible means of tailoring the properties of ABO 3 perovskite thin films. The effect of epitaxial strain on the structure of the perovskite unit cell can induce a host of interesting effects, these arising from either polar cation shifts or rotation of the oxygen octahedra, or both. In the multiferroic perovskite bismuth ferrite (BiFeO 3 -BFO), both degrees of freedom exist, and thus a complex behaviour may be expected as one plays with epitaxial strain. In this paper, we review our results on the role 2014 The Author(s) Published by the Royal Society. All rights reserved. of strain on the ferroic transition temperatures and ferroic order parameters. We find that, while the Néel temperature is almost unchanged by strain, the ferroelectric Curie temperature strongly decreases as strain increases in both the tensile and compressive ranges. Also unexpected is the very weak influence of strain on the ferroelectric polarization value. Using effective Hamiltonian calculations, we show that these peculiar behaviours arise from the competition between antiferrodistortive and polar instabilities. Finally, we present results on the magnetic order: while the cycloidal spin modulation present in the bulk survives in weakly strained films, it is destroyed at large strain and replaced by pseudo-collinear antiferromagnetic ordering. We discuss the origin of this effect and give perspectives for devices based on strain-engineered BiFeO 3 .

Measuring the magnetoelectric effect across scales

“…It is hard to model such a system as not only the desired orientation effect but also a completely different morphology applies for certain films and not for others (Pitfall 3). Complete coverage and nearly ideal interfaces have been obtained for other routes [76][77][78]. Concurrently, the introduction of dislocations has been found to play a large role at outer interfaces of ferroelectrics [76].…”

“…Another method to introduce stress transformation from one phase to another can be performed by material engineering through epitaxial growth of two different crystals with a lattice mismatch of up to 5% [76,78]. Inducing a strain by a corresponding field related to a certain material will evoke stress in the other phase thus tuning the material properties of the non active phase [101].…”

Electric-Field Induced Reversible Switching of the Magnetic Easy Axis in Co/BiFeO3 on SrTiO3

“…These results are presented in the supplementary materials. We note that previous studies have shown that the magnetic structure of these materials is very sensitive to strain, growth direction, and synthesis conditions 28,29 .…”

Selected multiferroic perovskite oxides containing rare earth and transition metal elements

“…First-principles calculations [36] even predict that by simply depositing the room-temperature FM double perovskites Bi 2 NiReO 6 and Bi 2 MnReO 6 on a substrate strain should turn their antipolar bulk ground state into a FE one. For the materials already showing bulk FE, strain engineering has also been shown to be a powerful and flexible means of tailoring the properties of ABO 3 thin films [37,38] or superlattices [39]. The effect of epitaxial strain on the structure of the perovskite unit cell can induce a host of interesting effects, arising from either polar cation shifts or rotation of the oxygen octahedra, or both.…”