Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT

Evans, Donald M.; Schilling, A.; Kumar, Ashok; Sanchez, Dilsom A.; Ortega, N.; Arredondo, Miryam; Katiyar, Ram S.; Gregg, J. M.; Scott, J. F.

doi:10.1038/ncomms2548

Cited by 158 publications

(157 citation statements)

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“…Evans et al 50 measure 5.5 Â 10 À8 sm À1 to 1.3 Â 10 À7 sm À1 for a 31 in 40:60 PFT/PZT at 293 K. These are very large values. We note also for completeness that PFN-PZT ceramic single-phase compounds were first studied in 1981 by Whatmore and Bell.…”

Section: Discussionmentioning

confidence: 99%

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

Sanchez

Ortega

Kumar

et al. 2013

Journal of Applied Physics

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113

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We describe extensive studies on a family of perovskite oxides that are ferroelectric and ferromagnetic at ambient temperatures. The data include x-ray diffraction, Raman spectroscopy, measurements of ferroelectric and magnetic hysteresis, dielectric constants, Curie temperatures, electron microscopy (both scanning electron microscope and transmission electron microscopy (TEM)) studies, and both longitudinal and transverse magnetoelectric constants α33 and α31. The study extends earlier work to lower Fe, Ta, and Nb concentrations at the B-site (from 15%–20% down to 5%). The magnetoelectric constants increase supralinearly with Fe concentrations, supporting the earlier conclusions of a key role for Fe spin clustering. The room-temperature orthorhombic C2v point group symmetry inferred from earlier x-ray diffraction studies is confirmed via TEM, and the primitive unit cell size is found to be the basic perovskite Z = 1 structure of BaTiO3, also the sequence of phase transitions with increasing temperature from rhombohedral to orthorhombic to tetragonal to cubic mimics barium titanate.

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Section: Discussionmentioning

confidence: 99%

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

Sanchez

Ortega

Kumar

et al. 2013

Journal of Applied Physics

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113

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“…In combination with PZT, its properties are not significantly dependent upon the Zr/Ti ratio; and in fact, pure PbTiO 3 works as well as PZT for most of these systems, as initially demonstrated with PFW. 53 Switching in PFT/PZT single-phase nano-crystals was reported by Evans et al, 54 as shown in Figure 8, using a submicron-diameter sample cut via focused-ion beam from a one-micron diameter grain in a bulk ball-milled ceramic. All tests show these samples to be single-phase, although under highresolution transmission electron microscopy some dark nano-spots were observed decorating the grain boundary.…”

Section: Lead-iron Perovskitesmentioning

confidence: 99%

“…25% P, and subsequent field reversals switch negligible amounts of polarization. 54 This implies either that the magnetically switched electric domains are somehow more easily pinned or that another mechanism is involved, possibly involving the nested ferroelastic twins and magnetostriction. One can switch from þ P to ÀP (a large value of ca.…”

Section: Lead-iron Perovskitesmentioning

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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“…That is, electronic conduction is similar to fluid dynamics, with vortex motion, and not limited by Bloch theory. At about the same time it was shown [3][4][5] that the ferroelastic domain walls in multiferroics 6 are also controlled by fluid mechanics, with both wrinkling [7][8][9] and folding 3,4 at certain velocity thresholds, and hence that the domain walls may be treated as ballistic objects in high-viscosity media [n.b., wrinkling involves smoothly curved periodic modulation of domain walls, whereas folding consists of nearly 180-degree changes in direction] . In this sense semi-classical convection processes seem to appear in systems with very different basic dynamics.…”

Section: P2mentioning

confidence: 99%

Hydrodynamics of domain walls in ferroelectrics and multiferroics: Impact on memory devices

Scott

Evans

Gregg

et al. 2016

Applied Physics Letters

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The standard "Kittel Law" for the thickness and shape of ferroelectric, ferroelastic, or ferromagnet domains assumes mechanical equilibrium. The present paper shows that such domains may be highly nonequilibrium, with unusual thicknesses and shapes. In lead germanate and multiferroic lead zirconate titanate iron tantalate domain wall instabilities resemble hydrodynamics (Richtmyer-Meshkov and Helfrich-Hursault, respectively).Normally in ferroelectrics or ferroelastics the domains are rectilinear with straight edges, and the domain widths satisfy the Landau-Lifshitz-Kittel relationship ("Kittel Law") as proportional to the square root of sample thickness. Here we present data on ferroelectric lead germanate and lead zirconate-titanate-iron-tantalate that exhibit curved circular or parabolic walls and violate the Kittel Law, demonstrating that they are nonequilibrium processes. These display similarities with the Richtmyer-Meshkov and Helfrich-Hursault instabilities in fluid mechanics and are good examples of the "domain glass" model of Salje and Carpenter. Their presence may be detrimental to multiferroic memory applications. p.2Very recently and very surprisingly the dynamics of electron transport in both graphene 1 and some low-temperature metals 2 have been shown to be dominated under some conditions by hydrodynamics. That is, electronic conduction is similar to fluid dynamics, with vortex motion, and not limited by Bloch theory. At about the same time it was shown 3-5 that the ferroelastic domain walls in multiferroics 6 are also controlled by fluid mechanics, with both wrinkling 7-9 and folding 3,4 at certain velocity thresholds, and hence that the domain walls may be treated as ballistic objects in high-viscosity media [n.b., wrinkling involves smoothly curved periodic modulation of domain walls, whereas folding consists of nearly 180-degree changes in direction] . In this sense semi-classical convection processes seem to appear in systems with very different basic dynamics.The application of hydrodynamic models to domain walls in ferroelectrics is however not The application of viscosity models to magnetic domains is even older; Skomski et al. 11 did that exactly twenty years ago. And this year Salje et al. [12][13][14] found that ferroelastics are described well by hydrodynamics. The modest breakthrough in the present case follows the recent paper by Scott, 3 which suggests that if indeed domain walls follow hydrodynamic flow, they should exhibit hydrodynamic instabilities also. And he p.3 showed rope-like folding instabilities. It is a modest paradigm shift to replace the equilibrium domain physics of the "Kittel Law" with these nonequilibrium dynamics.In the present paper we examine data for two systems: Lead germanate, which importantly is NOT ferroelastic, which we examine on a mesoscopic domain scale (microns) and lowfield scale; and lead zirconate-titanate iron tantalate, which is ferroelastic and which we examine on a nm-domain scale.The wrinkling-folding instability critical field E f is...

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Magnetic switching of ferroelectric domains at room temperature in multiferroic PZTFT

Cited by 158 publications

References 41 publications

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

Room-temperature multiferroic magnetoelectrics

Hydrodynamics of domain walls in ferroelectrics and multiferroics: Impact on memory devices

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