Domain boundary engineering

Salje, Ekhard K. H.; Zhang, Huali

doi:10.1080/01411590902936138

Cited by 138 publications

(101 citation statements)

References 109 publications

(120 reference statements)

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“…Less widely known was, perhaps, that ferroelastic twin walls, spanning a few unit cells in width, are exceptional physical nano-objects with remarkable properties [2,3], being a notable example the observation of superconductivity at the ferroelastic domain walls of doped WO 3 [4]. Indeed, ferroelastic, or twin, walls are also inherent symmetry-breaking entities within a given material, with the potential to display the distinct additional physical responses associated to that fact.…”

Section: Introductionmentioning

confidence: 99%

Local conductivity and the role of vacancies around twin walls of (001)−BiFeO3 thin films

Farokhipoor¹,

Noheda²

2012

Journal of Applied Physics

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BiFeO3 thin films epitaxially grown on SrRuO3-buffered (001)-oriented SrTiO3 substrates show orthogonal bundles of twin domains, each of which contains parallel and periodic 71 o domain walls. A smaller amount of 109 o domain walls are also present at the boundaries between two adjacent bundles. All as-grown twin walls display enhanced conductivity with respect to the domains during local probe measurements, due to the selective lowering of the Schottky barrier between the film and the AFM tip (see S. Farokhipoor and B. Noheda, Phys. Rev. Lett. 107, 127601 (2011)). In this paper we further discuss these results and show why other conduction mechanisms are discarded. In addition we show the crucial role that oxygen vacancies play in determining the amount of conduction at the walls. This prompts us to propose that the oxygen vacancies migrating to the walls locally lower the Schottky barrier. This mechanism would then be less efficient in non-ferroelastic domain walls where one expects no strain gradients around the walls and thus (assuming that walls are not charged) no driving force for accumulation of defects.

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Section: Introductionmentioning

confidence: 99%

Local conductivity and the role of vacancies around twin walls of (001)−BiFeO3 thin films

Farokhipoor¹,

Noheda²

2012

Journal of Applied Physics

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“…As the DWs can be easily tuned by external fields, this opens the possibility of domain-boundary engineering and applications in microelectronics using the nanoscale DWs instead of the domains themselves as active device elements [9,10,11,12,13]. The hexagonal manganites seem especially suited for this kind of functionality: Their DWs are robust and represent persistent interfaces as they are attached to the vortex cores, but within these constraints they can be moved by an external field thus enabling switching [4,12,13].…”

mentioning

confidence: 99%

Conductivity Contrast and Tunneling Charge Transport in the Vortexlike Ferroelectric Domain Patterns of Multiferroic Hexagonal YMnO3

et al. 2017

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We deduce the intrinsic conductivity properties of the ferroelectric domain walls around the topologically protected domain vortex cores in multiferroic YMnO3. This is achieved by performing a careful equivalent-circuit analysis of dielectric spectra measured in single-crystalline samples with different vortex densities. The conductivity contrast between the bulk domains and the less conducting domain boundaries is revealed to reach up to a factor 500 at room temperature, depending on sample preparation. Tunneling of localized defect charge carriers is the dominant charge-transport process in the domain walls that are depleted of mobile charge carriers. This work demonstrates that via equivalent-circuit analysis, dielectric spectroscopy can provide valuable information on the intrinsic charge-transport properties of ferroelectric domain walls, which is of high relevance for the design of new domain-wall-based microelectronic devices.The hexagonal manganites RMnO3 (R = Sc, Y, In, and Dy-Lu) form a unique group of multiferroics where a geometrically-driven mechanism triggers improper ferroelectricity [1]. Additional interest in this material class arose from the reported occurrence of vortex-like ferroelectric domain patterns [2,3,4]. Around the vortex cores, forming the centers of "cloverleaf" patterns of six domains, the polarization changes sign six times. These cores, evolving at a high-temperature structural transition [5], represent stable topological defects. Even strong electric fields only lead to a variation of ferroelectric domain sizes in these materials, but are unable to completely eradicate unfavorable domains and to generate a mono-domain state [2,6]. Moreover, there is a strict coupling of ferroelectric and antiferromagnetic domain walls (DWs), the latter forming at much lower temperatures around 100 K [7].Recently it was shown that these complex domain properties also may be of relevance from an application point of view: Conductive atomic-force microscopy (c-AFM) on ErMnO3 [4] and HoMnO3 [8] revealed that the conductance of the ferroelectric DWs is either enhanced or suppressed compared to the domains, being determined by the polarization orientation of the adjacent domains. As the DWs can be easily tuned by external fields, this opens the possibility of domain-boundary engineering and applications in microelectronics using the nanoscale DWs instead of the domains themselves as active device elements [9,10,11,12,13]. The hexagonal manganites seem especially suited for this kind of functionality: Their DWs are robust and represent persistent interfaces as they are attached to the vortex cores, but within these constraints they can be moved by an external field thus enabling switching [4,12,13].In general, insulating domain walls, also observed in various other systems as SrMnO3 thin films [14] and (Ca,Sr)3Ti2O7 [15], have shifted into the focus of interest, due to their possible applications, e.g., as rewritable nanocapacitors. The conductivity contrast between these DWs and the domains should be...

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“…In particular, the polarity mismatch at charged walls leads to characteristics that clearly distinguish them from the interior of the domains they separate [1][2][3][4] . Such ferroelectric domain walls can behave as a two-dimensional insulator 5 , become metallic 6,7 , show orientation-dependent electrical conductance [8][9][10] or anisotropic magnetoresistance 11 , even when the bulk material has none of these properties.…”

mentioning

confidence: 99%

Polarization control at spin-driven ferroelectric domain walls

et al. 2015

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Unusual electronic states arise at ferroelectric domain walls due to the local symmetry reduction, strain gradients and electrostatics. This particularly applies to improper ferroelectrics, where the polarization is induced by a structural or magnetic order parameter. Because of the subordinate nature of the polarization, the rigid mechanical and electrostatic boundary conditions that constrain domain walls in proper ferroics are lifted. Here we show that spin-driven ferroelectricity promotes the emergence of charged domain walls. This provides new degrees of flexibility for controlling domain-wall charges in a deterministic and reversible process. We create and position a domain wall by an electric field in Mn 0.95 Co 0.05 WO 4 . With a magnetic field we then rotate the polarization and convert neutral into charged domain walls, while its magnetic properties peg the wall to its location. Using atomistic Landau-Lifshitz-Gilbert simulations we quantify the polarization changes across the two wall types and highlight their general occurrence.

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Domain boundary engineering

Cited by 138 publications

References 109 publications

Local conductivity and the role of vacancies around twin walls of (001)−BiFeO3 thin films

Local conductivity and the role of vacancies around twin walls of (001)−BiFeO3 thin films

Conductivity Contrast and Tunneling Charge Transport in the Vortexlike Ferroelectric Domain Patterns of Multiferroic Hexagonal YMnO3

Polarization control at spin-driven ferroelectric domain walls

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