226
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Managave SR, Ramesh R. Isotope Dendroclimatology: A Review with a Special Emphasis on Tropics. ADVANCES IN ISOTOPE GEOCHEMISTRY 2012. [DOI: 10.1007/978-3-642-10637-8_38] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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227
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Das S, Du AY, Gopal R, Ramesh R. Risk Management and Optimal Pricing in Online Storage Grids. INFORMATION SYSTEMS RESEARCH 2011. [DOI: 10.1287/isre.1100.0288] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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228
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Ko KT, Jung MH, He Q, Lee JH, Woo CS, Chu K, Seidel J, Jeon BG, Oh YS, Kim KH, Liang WI, Chen HJ, Chu YH, Jeong YH, Ramesh R, Park JH, Yang CH. Concurrent transition of ferroelectric and magnetic ordering near room temperature. Nat Commun 2011; 2:567. [DOI: 10.1038/ncomms1576] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 10/28/2011] [Indexed: 11/09/2022] Open
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229
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Baek SH, Park J, Kim DM, Aksyuk VA, Das RR, Bu SD, Felker DA, Lettieri J, Vaithyanathan V, Bharadwaja SSN, Bassiri-Gharb N, Chen YB, Sun HP, Folkman CM, Jang HW, Kreft DJ, Streiffer SK, Ramesh R, Pan XQ, Trolier-McKinstry S, Schlom DG, Rzchowski MS, Blick RH, Eom CB. Giant piezoelectricity on Si for hyperactive MEMS. Science 2011; 334:958-61. [PMID: 22096193 DOI: 10.1126/science.1207186] [Citation(s) in RCA: 341] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.
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230
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Heron JT, Trassin M, Ashraf K, Gajek M, He Q, Yang SY, Nikonov DE, Chu YH, Salahuddin S, Ramesh R. Electric-field-induced magnetization reversal in a ferromagnet-multiferroic heterostructure. PHYSICAL REVIEW LETTERS 2011; 107:217202. [PMID: 22181917 DOI: 10.1103/physrevlett.107.217202] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Indexed: 05/12/2023]
Abstract
A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.
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231
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Zhang JX, He Q, Trassin M, Luo W, Yi D, Rossell MD, Yu P, You L, Wang CH, Kuo CY, Heron JT, Hu Z, Zeches RJ, Lin HJ, Tanaka A, Chen CT, Tjeng LH, Chu YH, Ramesh R. Microscopic origin of the giant ferroelectric polarization in tetragonal-like BiFeO(3). PHYSICAL REVIEW LETTERS 2011; 107:147602. [PMID: 22107234 DOI: 10.1103/physrevlett.107.147602] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Indexed: 05/12/2023]
Abstract
We report direct experimental evidence for a room-temperature, ∼130 μC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
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232
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Seidel J, Fu D, Yang SY, Alarcón-Lladó E, Wu J, Ramesh R, Ager JW. Efficient photovoltaic current generation at ferroelectric domain walls. PHYSICAL REVIEW LETTERS 2011; 107:126805. [PMID: 22026787 DOI: 10.1103/physrevlett.107.126805] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 07/02/2011] [Indexed: 05/21/2023]
Abstract
We elucidate the mechanism of a newly observed photovoltaic effect which occurs in ferroelectrics with periodic domain structures. Under sufficiently strong illumination, domain walls function as nanoscale generators of the photovoltaic current. The steps in the electrostatic potential function to accumulate electrons and holes on opposite sides of the walls while locally reducing the concentration of the oppositely charged carriers. As a result, the recombination rate adjacent to the walls is reduced, leading to a net diffusion current. In open circuit, photovoltages for periodically ordered domain walls are additive and voltages much larger than the band gap can be generated. The internal quantum efficiency for individual domain walls can be surprisingly high, approaching 10% for above band-gap photons. Although we have found the effect in BiFeO(3) films, it should occur in any system with a similar periodic potential.
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233
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Krishnamoorthy P, Sathyadevi P, Senthilkumar K, Muthiah PT, Ramesh R, Dharmaraj N. Copper(I) hydrazone complexes: Synthesis, structure, DNA binding, radical scavenging and computational studies. INORG CHEM COMMUN 2011. [DOI: 10.1016/j.inoche.2011.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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234
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Jayakumari VG, Shamsudeen RK, Ramesh R, Mukundan T. Modeling and validation of polyurethane based passive underwater acoustic absorber. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:724-730. [PMID: 21877787 DOI: 10.1121/1.3605670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The acoustic behavior of an acoustically transparent polyurethane and an interpenetrating polymer network of polyurethane with polydimethyl siloxane were studied using dynamic mechanical analysis, finite element modeling, and experimental evaluation of acoustic properties in a water-filled pulse tube setup. Dynamic mechanical measurements in the temperature range -50 °C to +70 °C were carried out, and the data were used for time temperature superposition to generate material behavior at high frequencies. These inputs were used for modeling the acoustic behavior of these materials using ATILA, which is a commercial finite element code, capable of computing transmission and reflection characteristics of materials. From this data, absorption characteristics were computed. The results were compared with the experimental results obtained using a water-filled pulse tube facility.
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235
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Maksymovych P, Pan M, Yu P, Ramesh R, Baddorf AP, Kalinin SV. Scaling and disorder analysis of local I-V curves from ferroelectric thin films of lead zirconate titanate. NANOTECHNOLOGY 2011; 22:254031. [PMID: 21572199 DOI: 10.1088/0957-4484/22/25/254031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Differential analysis of current-voltage characteristics, obtained on the surface of epitaxial films of ferroelectric lead zirconate titanate (Pb(Zr(0.2)Ti(0.8))O(3)) using scanning probe microscopy, was combined with spatially resolved mapping of variations in local conductance to differentiate between candidate mechanisms of local electronic transport and the origin of disorder. Within the assumed approximations, electron transport was inferred to be determined by two mechanisms depending on the magnitude of applied bias, with the low-bias range dominated by the trap-assisted Fowler-Nordheim tunneling through the interface and the high-bias range limited by the hopping conduction through the bulk. Phenomenological analysis of the I-V curves has further revealed that the transition between the low- and high-bias regimes is manifested both in the strength of variations within the I-V curves sampled across the surface, as well as the spatial distribution of conductance. Spatial variations were concluded to originate primarily from the heterogeneity of the interfacial electronic barrier height with an additional small contribution from random changes in the tip-contact geometry.
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236
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Sundarapandiyan S, Brutto PE, Siddhartha G, Ramesh R, Ramanaiah B, Saravanan P, Mandal AB. Enhancement of chromium uptake in tanning using oxazolidine. JOURNAL OF HAZARDOUS MATERIALS 2011; 190:802-809. [PMID: 21536383 DOI: 10.1016/j.jhazmat.2011.03.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 05/30/2023]
Abstract
Monocyclic and bicyclic oxazolidines were offered at three different junctures of chrome tanning process viz. prior to BCS offer, along with BCS and after basification. It was found that oxazolidine when offered after basification brought about better chromium uptake and reduction of chromium load in the wastewater. Offer of oxazolidine was also varied. Increase in offer of oxazolidine from 0.25% to 1% was found to enhance the chromium uptake and decrease the chromium load in wastewater. But the increase in uptake was not proportionate to the increase in oxazolidine offer more than 0.75%. Offer of 1% Zoldine ZA 78 (monocyclic oxazolidine) and Zoldine ZE (bicyclic oxazolidine) after basification brought about 63.4% and 73.1% enhancement in chrome content in leather compared to control where oxazolidine was not offered. The tone of the wetblue was found to be altered moderately. However this did not call for any process adjustments in wet-finishing. The oxazolidine treated leathers were found to be immensely fuller and tighter. It was found experimentally that offer of 1% of oxazolidine facilitated reduction in the offer of syntans administered for filling and grain tightening by around 46%. Oxazolidine could bring about significant reduction in cost of chemicals apart from resulting environmental benefits due to enhancement of chromium uptake during tanning.
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237
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Chang HJ, Kalinin SV, Morozovska AN, Huijben M, Chu YH, Yu P, Ramesh R, Eliseev EA, Svechnikov GS, Pennycook SJ, Borisevich AY. Atomically resolved mapping of polarization and electric fields across ferroelectric/oxide interfaces by Z-contrast imaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:2474-2479. [PMID: 21538586 DOI: 10.1002/adma.201004641] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Indexed: 05/30/2023]
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238
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Du AY, Das S, Gopal RD, Ramesh R. Risk hedging in storage grid markets. ACM TRANSACTIONS ON MANAGEMENT INFORMATION SYSTEMS 2011. [DOI: 10.1145/1985347.1985351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Internet storage services allow businesses to move away from maintaining their own internal storage networks. Service providers currently follow a utility pricing model which translates to them absorbing all the risk that arises from the fluctuating storage needs of their customers. The risk borne by the Internet storage service providers has large revenue implications as Internet startups and smaller companies, which face significant demand stochasticity, constitute an important segment of their clientele. We develop an option pricing mechanism to hedge against this risk and evaluate its effectiveness vis-à-vis forward contracts. We obtain the conditions under which options dominate forward contracts and the trade-offs involved when the provider has to decide on appropriate pricing mechanisms. Our empirical study uses publicly obtainable traffic data of Amazon S3 clients to validate the analytical results. We show that providers can significantly benefit from including options in their risk-hedging portfolio, especially when there is less variation in the costs faced by the buyers in building their own data networks as opposed to using cloud services.
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239
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Maksymovych P, Seidel J, Chu YH, Wu P, Baddorf AP, Chen LQ, Kalinin SV, Ramesh R. Dynamic conductivity of ferroelectric domain walls in BiFeO₃. NANO LETTERS 2011; 11:1906-12. [PMID: 21486089 DOI: 10.1021/nl104363x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Topological walls separating domains of continuous polarization, magnetization, and strain in ferroic materials hold promise of novel electronic properties, that are intrinsically localized on the nanoscale and that can be patterned on demand without change of material volume or elemental composition. We have revealed that ferroelectric domain walls in multiferroic BiFeO(3) are inherently dynamic electronic conductors, closely mimicking memristive behavior and contrary to the usual assumption of rigid conductivity. Applied electric field can cause a localized transition between insulating and conducting domain walls, tune domain wall conductance by over an order of magnitude, and create a quasicontinuous spectrum of metastable conductance states. Our measurements identified that subtle and microscopically reversible distortion of the polarization structure at the domain wall is at the origin of the dynamic conductivity. The latter is therefore likely to be a universal property of topological defects in ferroelectric semiconductors.
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240
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Zhou SY, Zhu Y, Langner MC, Chuang YD, Yu P, Yang WL, Cruz Gonzalez AG, Tahir N, Rini M, Chu YH, Ramesh R, Lee DH, Tomioka Y, Tokura Y, Hussain Z, Schoenlein RW. Ferromagnetic enhancement of CE-type spin ordering in (Pr,Ca)MnO3. PHYSICAL REVIEW LETTERS 2011; 106:186404. [PMID: 21635110 DOI: 10.1103/physrevlett.106.186404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Indexed: 05/30/2023]
Abstract
We present resonant soft x-ray scattering results from small bandwidth manganites (Pr,Ca)MnO(3), which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic state and CE-type ordering.
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241
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Chiu YP, Chen YT, Huang BC, Shih MC, Yang JC, He Q, Liang CW, Seidel J, Chen YC, Ramesh R, Chu YH. Atomic-scale evolution of local electronic structure across multiferroic domain walls. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:1530-1534. [PMID: 21449056 DOI: 10.1002/adma.201004143] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 12/14/2010] [Indexed: 05/30/2023]
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242
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Ganpule CS, Roytburd AL, Nagarajan V, Stanishevsky A, Melngailis J, Williams ED, Ramesh R. Nanoscale electromechanical phenomena in ferroelectric thin films. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-655-cc1.5.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractFocused ion beam milling was used to fabricate ferroelectric islands in Pb-Zr-Ti-O thin films. The islands ranged in size from 200μm×200μm to 0.3μm×0.3μm. The inverse piezoelectric effect was studied in these islands as a function of their size by tracking the surface displacement of the top electrode of the island (under an applied electric field) using an atomic force microscope (AFM). It was found that there was a substantial increase in the piezoresponse as the size of the island decreased below 100μm×100μm. This increase was attributed to the elastic deformation of the substrate.
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243
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Polking MJ, Urban JJ, Milliron DJ, Zheng H, Chan E, Caldwell MA, Raoux S, Kisielowski CF, Ager JW, Ramesh R, Alivisatos AP. Size-dependent polar ordering in colloidal GeTe nanocrystals. NANO LETTERS 2011; 11:1147-1152. [PMID: 21338071 DOI: 10.1021/nl104075v] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The question of the nature and stability of polar ordering in nanoscale ferroelectrics is examined with colloidal nanocrystals of germanium telluride (GeTe). We provide atomic-scale evidence for room-temperature polar ordering in individual nanocrystals using aberration-corrected transmission electron microscopy and demonstrate a reversible, size-dependent polar-nonpolar phase transition of displacive character in nanocrystal ensembles. A substantial linear component of the distortion is observed, which is in contrast with theoretical reports predicting a toroidal state.
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244
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Sands T, Harbison J, Palmstrøm C, Ramesh R, Keramidas V. A Template Approach to Metal/III-V Semiconductor Epitaxy. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-221-271] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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245
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Tarascon JM, LePage Y, McKinnon WR, Tselepis E, Barboux P, Bagley B, Ramesh R. On the Origin of the Structural Modulation in the Bi Cuprates As Derived from 3d-Metal Substituted Phases. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-156-317] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTA substitution for Cu by a 3d-metal (Fe, Co, Mn) in the superconducting Bi phases (Bi2Sr2Can−1CunOy; n = 1,2 and 3) has led to the discovery of new phases. These 3d-metal substituted phases are non-superconducting and, in contrast to the Cu-based phases, they exhibit a structural modulation that is commensurate. Single crystal x-ray studies were performed on the Bi2Sr3Fe2Oy, Bi2Sr2CoOy and Bi2Sr2MnOy compounds. A result, in common, is that the modulation is caused by the periodic insertion of a row of oxygen atoms in the Bi layers and this results in a corrugated-like slab structure. The Bi-O layers can be described as composed of alternating rocksalt-type and oxygen deficient perovskite-type blocks. For the Fe (n=2) phase the Bi atoms form ribbons (chains) in the ab plane. This is in contrast to the n=1 Co or Mn phases for which a disorder at the oxygen position is observed. Although the extra oxygen in the Bi-O layer could account for the doping mechanism in the high Tc Bi-phases, cation non-stoichiometry may also beimportant.
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246
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Wu XD, Venkatesan T, Inam A, Xi XX, Li Q, McLean WL, Chang CC, Hwang DM, Ramesh R, Nazar L, Wilkens B, Schwarz SA, Ravi RT, Martinez JA, England P, Tarascon JM, Muenchausen RE, Foltyn S, Estler RC, Dye RC, Garcia AR, Nogar NS. Pulsed Laser Deposition of High Tc Superconducting thin Films: Present and Future. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-191-129] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPulsed laser deposition (PLD) has been widely used for deposition of high Tc superconducting thin films, and is recognized as one of the best physical vapor techniques for the preparation of these films. The most important advantage of this technique is stoichiometric deposition; films can be made with the same composition as the target. Utilizing PLD, not only thin films but also multilayers and superlattices of high Tc superconductors have been fabricated. In this paper, the performance of the technique will be reviewed, and speculations regarding the future would be made.
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247
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Warren WL, Dimos D, Tuttle BA, Pike GE, Raymond MV, Nasby RD, Ramesh R, Evans JT. Mechanism(s) for the Suppression of the Switchable Polarization in PZT and BaTiO3. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-361-51] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTSwitchable polarization can be significantly suppressed in ferroelectric (FE) materials by optical, thermal, and electrical processes. The thermal process can occur by either annealing the FE in a reducing environment or by heating it in air to 100°C while impressing a bias near the switching threshold. The optical process occurs while biasing the FE near the switching threshold and illuminating with bandgap light. And the electrical suppression effect occurs by subjecting the FE to repeated polarization reversals. Using electron paramagnetic resonance, polarization-vol tage measurements, and charge injection scenarios, we have been able to elucidate both electronic and ionic trapping effects that lead to a suppression in the amount of switchable polarization in FE materials. The relative roles of electronic and ionic effects in the same material can depend on the stress condition. For instance, in oxidized BaTiO3 crystals, optical and thermal suppressions occur by electronic domain pinning; electrical fatigue in the BaTiO3 crystals also appears to involve electronic charge trapping, however, it is suggested that these electronic traps are further stabilized by nearby ionic defects. In sol-gel PZT thin films with either Pt, RuO2, or La-Sr-Co-O electrodes it appears that the polarization suppression induced by electrical fatigue, a temperature/bias combination, or a light/bias combination are all primarily due to the trapping of electronic charge carriers to first order.
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248
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Eatough MO, Dimos D, Tuttle BA, Warren WL, Ramesh R. A Study of Switching Behavior in Pb(Zr,Ti) O3 Thin Films Using X-Ray Diffraction. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-361-111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPb(Zr,Ti)O3 (PZT) thin films are being developed for use in optical and electronic memory devices. To study ferroelectric switching behavior, we have produced relatively untextured PZT thin films on Si substrates. We have developed a method for using x-ray diffraction to observe domain switching in situ. Our study involved the use of a micro-diffractometer to monitor the switching behavior in relatively small (0.7mm diameter) electroded areas. Diffraction analyses were done while DC voltages were applied and removed, representing several places in the hysteresis loop. In particular, we were looking for relative intensity changes in the [h 00],[00l] diffraction peaks as a function of position in the hysteresis loop. Our study indicates that the 90° domain switching exhibited by bulk ferroelectrics, is very limited in films on Si when grain sizes are less than about 1 μm.
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249
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Alpay SP, Prakash AS, Aggarwal S, Ramesh R, Roytburd AL, Shuk P, Greenblatt M. Polydomain Structure of Epitaxial PbTiO3 films on MgO. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-493-111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTA PbTiO3(001) film grown on MgO(001) by pulsed laser deposition is examined as an example to demonstrate the applications of the domain stability map for epitaxial perovskite films which shows regions of stable domains and fractions of domains in a polydomain structure. X-ray diffraction studies indicate that the film has a …c/a/c/a… domain structure in a temperature range of °C to 400°C with the fraction of c-domains decreasing with increasing temperature. These experimental results are in excellent agreement with theoretical predictions based on the stability map.
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250
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Gruverman A, Prakash SA, Aggarwal S, Ramesh R, Auciello O, Tokumoto H. Nanoscale Investigation of Polarization Retention Loss in Ferroelectric Thin Films VIA Scanning Force Microscopy. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-493-53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTScanning force microscopy (SFM) was applied to direct nanoscale investigation of the mechanism of retention loss in ferroelectric thin films. Experiments were conducted by performing local polarization reversal within an individual grain with subsequent imaging of a resulting domain structure at various time intervals. A conductive SFM tip was used for domain switching and imaging in the SFM piezoresponse mode.
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