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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Subject: search.filters.subject.domain wall

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Now showing 1 - 4 of 4
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    Dynamic Conductivity of Ferroelectric Domain Walls in BiFeO3
    (2011-05-01)
    Maksymovych, Peter
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    Seidel, Jan
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    Chu, Ying Hao
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    Wu, Pingping
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    Baddorf, Arthur P.
    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 BiFeO3 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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    Magnetoresistance study of patterned permalloy nanostructures
    (2008-05-01)
    Chen, D. C.
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    Mei, J. K.
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    Wang, Y.
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    Yao, Y. D.
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    Wu, J. K.
    We demonstrated the domain wall motion along the direction of the perimeter of a permalloy ring in the onion state. From the magnetoresistance (MR) measurement with a rotating ring at different constant fields, the critical field to form the onion state is near 200 Gauss and the lowest field that can still drag the domain wall is between 20 and 10 Gauss. The results also revealed a tendency for angle shifting and indicated that the lowest field component in the perimeter direction (the tangential component) was near 10 Gauss at an applied field of 20 Gauss.
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    Electromechanical Coupling among Edge Dislocations, Domain Walls, and Nanodomains in BiFeO3 Revealed by Unit-Cell-Wise Strain and Polarization Maps
    (2013-04-01)
    Lubk, A.
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    Rossell, M. D.
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    Seidel, J.
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    Chu, Y. H.
    ;
    Ramesh, R.
    The performance of ferroelectric devices, for example, the ferroelectric field effect transistor, is reduced by the presence of crystal defects such as edge dislocations. For example, it is well-known that edge dislocations play a crucial role in the formation of ferroelectric dead-layers at interfaces and hence finite size effects in ferroelectric thin films. The detailed lattice structure including the relevant electromechanical coupling mechanisms in close vicinity of the edge dislocations is, however, not well-understood, which hampers device optimization. Here, we investigate edge dislocations in ferroelectric BiFeO3 by means of spherical aberration-corrected scanning transmission electron microscopy, a dedicated model-based structure analysis, and phase field simulations. Unit-cell-wise resolved strain and polarization profiles around edge dislocation reveal a wealth of material states including polymorph nanodomains and multiple domain walls characteristically pinned to the dislocation. We locally determine the piezoelectric tensor and identify piezoelectric coupling as the driving force for the observed phenomena, explaining, for example, the orientation of the domain wall with respect to the edge dislocation. Furthermore, an atomic model for the dislocation core is derived.
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    Tunable Metallic Conductance in Ferroelectric Nanodomains
    (2012-01-01)
    Maksymovych, Peter
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    Morozovska, Anna N.
    ;
    Yu, Pu
    ;
    Eliseev, Eugene A.
    ;
    Chu, Ying-Hao
    Metallic conductance in charged ferroelectric domain walls was predicted more than 40 years ago as the first example of an electronically active homointerface in a nonconductive material. Despite decades of research on oxide interfaces and ferroic systems, the metal-insulator transition induced solely by polarization charges without any additional chemical modification has consistently eluded the experimental realm. Here we show that a localized insulator-metal transition can be repeatedly induced within an insulating ferroelectric lead-zirconate titanate, merely by switching its polarization at the nanoscale. This surprising effect is traced to tilted boundaries of ferroelectric nanodomains, that act as localized homointerfaces within the perovskite lattice, with inherently tunable carrier density. Metallic conductance is unique to nanodomains, while the conductivity of extended domain walls and domain surfaces is thermally activated. Foreseeing future applications, we demonstrate that a continuum of nonvolatile metallic states across decades of conductance can be encoded in the size of ferroelectric nanodomains using electric field.