Flexocoupling impact on the kinetics of polarization reversal

Vorotiahin, Ivan S.; Morozovska, Anna N.; Eliseev, Eugene A.; Genenko, Yuri A.

doi:10.1103/physrevb.95.014104

Cited by 7 publications

(2 citation statements)

References 68 publications

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“…It was experimentally proved that, as shown in Fig. 11(c), the mechanical force shows a comparable ability relative with the electrically method for switching the domain of the Moreover, with the help of flexoelectricity, the self-polarization direction of ferroelectric thin films, which is of difficulty in control in previous studies, is feasible to be changed by tuning the substrate interfaces and film thicknesses [153,154]. Park et al [155] demonstrated that the multiple domain switching pathways in multiaxial ferroelectric materials can be selectively controlled by a newly realized trailing flexoelectric field, specifically, by the motion of a mechanically loaded scanning probe microscope tip.…”

Section: Domain Tailoring and Polarization Switchingmentioning

confidence: 93%

Flexoelectric materials and their related applications: A focused review

et al. 2019

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Flexoelectricity refers to the mechanical-electro coupling between strain gradient and electric polarization, and conversely, the electro-mechanical coupling between electric field gradient and mechanical stress. This unique effect shows a promising size effect which is usually large as the material dimension is shrunk down. Moreover, it could break the limitation of centrosymmetry, and has been found in numerous kinds of materials which cover insulators, liquid crystals, biological materials, and semiconductors. In this review, we will give a brief report about the recent discoveries in flexoelectricity, focusing on the flexoelectric materials and their applications. The theoretical developments in this field are also addressed. In the end, the perspective of flexoelectricity and some open questions which still remain unsolved are commented upon.

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Section: Domain Tailoring and Polarization Switchingmentioning

confidence: 93%

Flexoelectric materials and their related applications: A focused review

et al. 2019

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“…Mechanical writing of stable nanodomains in simple mono-domain ultrathin BaTiO 3 films or 100 nm-thick BiFeO 3 films, by applying a non-uniform loading force using the surface probe in PFM, has been reported by several groups [278][279][280][281]. The underlying mechanism of these observed mechanical switching phenomena is now widely accepted as a flexoelectric effect, which is caused by the strong coupling between polarization and strain gradient induced by the probe-induced non-uniform force [278,282,283]. Similar switching phenomena of writing stable nanodomains in BaTiO 3 or BiFeO 3 films have so far not been observed in in situ TEM.…”

Section: Mechanical Switchingmentioning

confidence: 98%

Real-time studies of ferroelectric domain switching: a review

Xie

Pan

2019

Rep. Prog. Phys.

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Ferroelectric materials have been utilized in a broad range of electronic, optical, and electromechanical applications and hold the promise for the design of future high-density nonvolatile memories and multifunctional nano-devices. The applications of ferroelectric materials stem from the ability to switch polarized domains by applying an electric field, and therefore a fundamental understanding of the switching dynamics is critical for design of practical devices. In this review, we summarize the progress in the study of the microscopic process of ferroelectric domain switching using recently developed in situ transmission electron microscopy (TEM). We first briefly introduce the instrumentation, experimental procedures, imaging mechanisms, and analytical methods of the state-of-the-art in situ TEM techniques. The application of these techniques to studying a wide range of complex switching phenomena, including domain nucleation, domain wall motion, domain relaxation, domaindefect interaction, and the interplay between different types of domains, is demonstrated. The underlying physics of these dynamic processes are discussed.

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Tuning the polar states of ferroelectric films via surface charges and flexoelectricity

Vorotiahin¹,

Eliseev²,

Li³

et al. 2017

Acta Materialia

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Using the self-consistent Landau-Ginzburg-Devonshire approach we simulate and analyze the spontaneous formation of the domain structure in thin ferroelectric films covered with the surface screening charge of the specific nature (Bardeen-type surface states). Hence we consider the competition between the screening and the domain formation as alternative ways to reduce the electrostatic energy and reveal unusual peculiarities of distributions of polarization, electric and elastic fields conditioned by the surface screening length and the flexocoupling strength. We have established that the critical thickness of the film and its transition temperature to a paraelectric phase strongly depend on the Bardeen screening length, while the flexocoupling affects the polarization rotation and closure domain structure and induces ribbon-like nano-scale domains in the film depth far from the top open surface. Hence the joint action of the surface screening (originating from e.g. the adsorption of ambient ions or surface states) and flexocoupling may remarkably modify polar and electromechanical properties of thin ferroelectric films. (A.N.M.) 2 I. INTRODUCTIONFerroelectric materials remain the object of endless fascination for applied and fundamental science alike. The fundamental aspect of these materials is the presence of surface and interface bound charges due to the discontinuity of the spontaneous polarization. Since the early days of ferroelectricity, these charges were recognized as the key aspect of the physics of ferroelectric surfaces and interfaces.Indeed, if the polarization charge were uncompensated, it would provide bulk-like contributions to the free energy of materials, i.e. the corresponding energy would diverge with the system size. These considerations stimulated the search for mechanisms for lowering of this depolarization energy. One such mechanism is formation of ferroelectric domains, extensively analyzed in classical textbooks [1,2 ]. The second is charge screening, either internal "bulk" screening by free charges inside a ferroelecric [3,4] or external "surface" screening by the free charges in the case of the open or electroded ferroelectric film surface. Surprisingly, until now the domain formation and surface screening mechanisms were considered separately, and the competition between these effects almost escaped the attention of scientific community, despite the fact that these processes are intertwined in thin films.Surface screening of the bound charges is typically provided by the mobile charges adsorbed from the ambience in the case of high or normal humidity [5,6,7,8,9] or by internal mobile charges of defect nature [10,11]. In a specific case of the very weak screening, or its artificial absence due to the experimental treatment (cleaned surface in dry atmosphere, ultra-high vacuum or thick dielectric layer at the surface) the screening charges can be localized at surface states caused by the strong bandbending by depolarization field [12,13,14,15,16,17]. For both aforementioned cases the s...

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Flexocoupling impact on the kinetics of polarization reversal

Abstract: The impact of flexoelectric coupling on polarization reversal kinetics and space charge dynamics in thin films of ferroelectric-semiconductors has been theoretically studied.

Cited by 7 publications

References 68 publications

Flexoelectric materials and their related applications: A focused review

Flexoelectric materials and their related applications: A focused review

Real-time studies of ferroelectric domain switching: a review

Tuning the polar states of ferroelectric films via surface charges and flexoelectricity

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