Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 thin films

Keeney, Lynette; Kulkarni, Santosh; Deepak, Nitin; Schmidt, Michael; Petkov, Nikolay; Zhang, Panfeng F.; Cavill, S. A.; Roy, Saibal; Pemble, Martyn E.; Whatmore, R. W.

doi:10.1063/1.4745936

Cited by 49 publications

(47 citation statements)

References 38 publications

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“…Note that there are no detectable lines from spinel (or indeed any other) minor phases visible in the XRD patterns of the films -the strongest (311) spinel reflections would be expected at 2θ=35.4°. However, the noise level in any XRD scan places a limit on the detectability on such minor phases and the method is intrinsically unable to detect trace levels (typically 1-3 vol %, depending on the relative compositions of secondary and parent phases) of strongly magnetic secondary phases which may affect the overall magnetization of the 54 Clearly, detailed microstructural assessment is required for any sample of this type to exclude this as a possibility, and ideally to place a confidence level on that exclusion.…”

Section: Finally the Field Is Removed And Magnetization Is Measured Wmentioning

confidence: 99%

Magnetic Field‐Induced Ferroelectric Switching in Multiferroic Aurivillius Phase Thin Films at Room Temperature

et al. 2013

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Single-phase multiferroic materials are of considerable interest for future memory and sensing applications. Thin films of Aurivillius phase Bi7Ti3Fe3O21 and Bi6Ti2.8Fe1.52Mn0.68O18 (possessing six and five perovskite units per half-cell, respectively) have been prepared by chemical solution deposition on c-plane sapphire. Superconducting quantum interference device magnetometry reveal Bi7Ti3Fe3O21 to be antiferromagnetic (TN = 190 K) and weakly ferromagnetic below 35 K, however, Bi6Ti2.8Fe1.52Mn0.68O18 gives a distinct room-temperature in-plane ferromagnetic signature (Ms = 0.74 emu/g, μ0Hc =7 mT). Microstructural analysis, coupled with the use of a statistical analysis of the data, allows us to conclude that ferromagnetism does not originate from second phase inclusions, with a confidence level of 99.5%. Piezoresponse force microscopy (PFM) demonstrates room-temperature ferroelectricity in both films, whereas PFM observations on Bi6Ti2.8Fe1.52Mn0.68O18 show Aurivillius grains undergo ferroelectric domain polarization switching induced by an applied magnetic field. Here, we show for the first time that Bi6Ti2.8Fe1.52Mn0.68O18 thin films are both ferroelectric and ferromagnetic and, demonstrate magnetic field-induced switching of ferroelectric polarization in individual Aurivillius phase grains at room temperature

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Section: Finally the Field Is Removed And Magnetization Is Measured Wmentioning

confidence: 99%

Magnetic Field‐Induced Ferroelectric Switching in Multiferroic Aurivillius Phase Thin Films at Room Temperature

et al. 2013

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“…8 Previous work undertaken on BTFO has shown it to be both ferroelectric, with a Curie temperature of about 730 C, 9 and to possess antiferromagnetic order, with a Neel point of 80 K. 10 The magneto-electric coupling behavior 11 and an obvious magnetocapacitance effect 12 have also been observed. By Nd-doping 13 or by substituting Fe with the Co 14 BTFO, solid-solution films have been reported to exhibit ferromagnetism to some degree, although recent work 15,16 has shown that great care must be taken, when interpreting ferromagnetic responses, to eliminate the effects of ferromagnetic second phases, even at very low levels. In addition, Jang et al 17 reported the photocatalytic and the photoelectrochemical performance of BTFO material for photo-current generation under visible light (k !…”

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confidence: 99%

“…The structural and piezoresponse properties of c-axis-oriented Aurivillius phase Bi 5 The deposition by atomic vapor deposition of highly c-axis-oriented Aurivillius phase Bi 5 Ti 3 FeO 15 (BTFO) thin films on (100) Si substrates is reported. Partially crystallized BTFO films with c-axis perpendicular to the substrate surface were first deposited at 610 C (8% excess Bi), and subsequently annealed at 820 C to get stoichiometric composition.…”

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confidence: 99%

“…[11][12][13][14][15][16][17][18][19] While methods such as sol-gel, 12,19 solid-state reaction, 17,18 and pulsed laser deposition 4 20,21 Atomic vapor deposition (AVD) is based on pulsed liquid-injection chemical vapor deposition with a volume of each pulse of the order of microlitres. 22 It has been proved that AVD can deposit high-quality high-k dielectric or ferroelectric films with a largely uniform film thickness, composition, and electrical properties and is highly suitable for mass production.…”

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The structural and piezoresponse properties of c-axis-oriented Aurivillius phase Bi5Ti3FeO15 thin films deposited by atomic vapor deposition

Zhang

Deepak

Keeney

et al. 2012

Applied Physics Letters

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The deposition by atomic vapor deposition of highly c-axis-oriented Aurivillius phase Bi 5Ti 3FeO 15 (BTFO) thin films on (100) Si substrates is reported. Partially crystallized BTFO films with c-axis perpendicular to the substrate surface were first deposited at 610°C (8 excess Bi), and subsequently annealed at 820°C to get stoichiometric composition. After annealing, the films were highly c-axis-oriented, showing only (00l) peaks in x-ray diffraction (XRD), up to (0024). Transmission electron microscopy (TEM) confirms the BTFO film has a clear layered structure, and the bismuth oxide layer interleaves the four-block pseudoperovskite layer, indicating the n 4 Aurivillius phase structure. Piezoresponse force microscopy measurements indicate strong in-plane piezoelectric response, consistent with the c-axis layered structure, shown by XRD and TEM

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“…66,67 Magnetoelectric Aurivilius phases. The realization that magnetic ions could be substituted into Aurivilius-phase ferroelectrics came independently from several sources, but it was ambiguous in these studies whether the magnetism M arose from small minor phases; even a tiny percentage by weight could produce the measured values of M. Keeney et al 68 have carried out careful measurements on an n ¼ 5 Aurivilius structure in which the B-site in each perovskite block is 70% filled with Fe and 30% with Co: they find that Figure 11). In addition, the n ¼ 5 Aurivilius structure (Figure 10 Figure 12 reproduces their polarization switching in a magnetic field of H ¼ 0.25 T at room temperature.…”

Section: Aurivilus-phase Ferrites Cobaltates and Manganitesmentioning

confidence: 99%

Room-temperature multiferroic magnetoelectrics

2013

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A short review is given of the recent work on single-phase crystals that are ferroelectric and ferromagnetic at or near room temperature. BiFeO 3 is mentioned only briefly, because it has been reviewed in detail elsewhere very recently; emphasis instead is on copper oxide, perovskite oxides with mixed B-site occupancy (such as Pb(Fe 1/2 Ta 1/2 ) x (Zr y Ti INTRODUCTIONMultiferroics are usually defined as single-phase crystals exhibiting at the same temperature and pressure both ferromagnetism (or antiferromagnetism) and ferroelectricity (or antiferroelectricity). As most ferroelectrics are also ferroelastic 1 (hysteretic stress-strain relationships), the 'multi-ferro' label often includes three coupled order parameters. (As a peripheral comment, we note that it is necessary and sufficient 2 for a ferroelectric to be ferroelastic if its phase transition changes the crystal class-for example, from orthorhombic to tetragonal-treating hexagonal and trigonal as a single super-class. Examples of nonferroelastic ferroelectrics include KTiOPO 4 and LiNbO 3 , whose ferroelectric transitions are, respectively, orhorhombic-orthorhombic and trigonal-trigonal.)The interest in multiferroics at present is growing rapidly, and the interest is twofold: from a fundamental point of view the coupling between spins and lattices in crystals-between magnetism and ferroelectricity and/or structural phase transitions-has been recognized as complex and fascinating for several decades, generally requiring low-symmetry materials that were carefully avoided in earlier days of solid state theory. A good reason why it is presented in the elegant work by Schmid and Trooster 3 on the boracites: These materials (for example, nickel-iodine boracite) are multiferroic only at cryogenic temperatures and grow in needle-like structures, making them impractical for commercial device applications; and theoretically they exhibit low symmetry (monoclinic or triclinic) and have as many as 96 atoms per unit cell, making them theoretically formidable. Despite these drawbacks, multiferroics present a possible avenue for the next generation of computer digital memories, combining at least in principle, the high-speed and low-power consumption 4,5 of a ferroelectric random access memory (FRAM) with the nondestructive READ operation of a magnetic RAM. We discuss below why these goals will not be easy to achieve in commercial products:The most serious problems are operational temperature (most multiferroics operate well below ambient) and magnitudes of magnetization (all multiferroics with reasonably high operating temperatures are weak ferromagnets-canted antiferromagnetswhereas a strong ferromagnet is desired), and the switched polarization is also extremely weak. The polarization in most multiferroics is so weak that authors measure it in nC m À2 rather than the older customary mC cm À2 . Keep in mind that equally good SI units would be C hectare À1 for these multiferroics, a value far lower than the roughly 1 mC cm À2 required by a computer memory sense ampl...

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Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 thin films

Cited by 49 publications

References 38 publications

Magnetic Field‐Induced Ferroelectric Switching in Multiferroic Aurivillius Phase Thin Films at Room Temperature

Magnetic Field‐Induced Ferroelectric Switching in Multiferroic Aurivillius Phase Thin Films at Room Temperature

The structural and piezoresponse properties of c-axis-oriented Aurivillius phase Bi5Ti3FeO15 thin films deposited by atomic vapor deposition

Room-temperature multiferroic magnetoelectrics

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