Interlayer strain effects on the structural behavior of BiFeO3/LaFeO3 superlattices

Abstract

Artificial (BiFeO3)0.5 /(LaFeO3)0.5 superlattices (SLs) have been grown by pulsed laser deposition. The periodicity was varied from 150 Å to 25 Å and the relative ratio between BFO and LFO is kept constant in each period. X-ray diffraction, transmission electron microscopy (TEM) and Raman spectroscopy investigations indicate antiferroelectric-like structures for large periodicity ( ≥76 Å) while Pnma LaFeO3-like structures are observed for small periodicity ≤50 Å. Room temperature Magnetic measurements were obtained by vibrating sample magnetometry and suggest antiferromagnetic ordering with weak ferromagnetism. Temperature dependent x-ray diffraction studies show an important shift 2 of paraelectric-antiferroelectric phase transition scaling with BFO thickness. Strain and size effects explain this behavior and discussion is also made of the possible role of the oxygen octahedral rotation/tilt degree of freedom.

Liberating a hidden antiferroelectric phase with interfacial electrostatic engineering

“…In superlattices of ferroelectric BiFeO 3 and paraelectric LaFeO 3 , a region of complex/ mixed-phase BiFeO 3 has been found for intermediate superlattice layers and attributed to a nanoscale twinned phase (23). In other superlattices of BiFeO 3 and LaFeO 3 , a PbZrO 3 -like antipolar BiFeO 3 phase has been identified and attributed to result from symmetry mismatch and strain (24,25). This is corroborated by additional DFT calculations showing that antiferroelectric phases can be induced from ferroelectrics as a result of interfacial charge (26) and related experimental work on short-period ferroelectric superlattices with confining dielectric layers (2) and short-period antiferroelectrics (27).…”

Anti-polar state in BiFeO3/NdFeO3 superlattices

“…The microscope was equipped with a spherical aberration correction (Cs) system and a contrast diaphragm of 60 μm. These regularly spaced satellite peaks are proof of a periodic chemical modulation along the out-of-plane growth direction [19]. It is not possible to assign a peculiar diffraction peak for BFO layers and one for the NFO layers.…”

“…Artificially modulated heterostructures such as superlattices (SLs) are also employed to better understand the competing interactions that exist within the MPB. For instance, BiFeO3/ LaFeO3 (BFO/LFO) SLs deposited on different substrates have been studied by different groups [17][18][19][20][21]. Interestingly, a strain-and symmetry-mismatch-induced stabilization of the AFE-like state was reported in BFO/LFO SLs [18].…”

“…SrTiO3 substrate [19,20]. Moreover, BiFeO3/Bi(1-x)SmxFeO3 SLs have been also fabricated using combinatorial PLD [22] and evidence of an AFE-like state and enhanced dielectric properties are reported [23].…”

Layer and spontaneous polarizations in perovskite oxides and their interplay in multiferroic bismuth ferrite

“…3d). For example, in superlattices and heterostructures of BiFeO 3 with centrosymmetric P nma LaFeO 3 , BiFeO 3 has been reported to adopt the antiferroelectric PbZrO 3 structure [57,58], or even observed in an entirely new antiferroelectric structure, which has not been reported in the bulk [15]. Density functional calculations indicated that, for the strain conditions of the sample, this antiferroelectric phase is only slightly higher in energy than the ground-state polar phase, and it is favored because of its lower electrostatic energy cost [15].…”