Large polarization gradients and temperature-stable responses in compositionally-graded ferroelectrics

Damodaran, Anoop R.; Pandya, Shishir; Qi, Yubo; Hsu, Shang‐Lin; Shi, Liyi; Nelson, Christopher T.; Dasgupta, Arvind; Ercius, Peter; Ophus, Colin; Dedon, Liv R.; Agar, Josh C.; Lu, H.; Zhang, Jialan; Minor, Andrew M.; Rappe, Andrew M.; Martin, Lane W.

doi:10.1038/ncomms14961

Cited by 71 publications

(63 citation statements)

References 54 publications

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“…Primarily, this has been achieved by placing a material in the vicinity of a phase transition driven either by chemistry or temperature where most ferroic susceptibilities diverge. More recently, advances in the growth of ferroic thin films has shown that epitaxial strain can be another route by which to manipulate ferroelectric order, ferroic susceptibilities, and domain structures . In turn, there has been extensive work in understanding the role of such ferroelectric/ferroelastic domains and domain walls on the dielectric and piezoelectric response.…”

Section: Thermophysical Properties (At 300 K) Of the Various Thin Filmentioning

confidence: 99%

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films

et al. 2018

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Temperature-dependent changes in spontaneous polarization (i.e., the pyroelectric effect or PEE) [1] have the potential to impact applications in waste-heat energy conversion [2,3] and thermal imaging. [4] Similarly, the inverse thermodynamic effect (i.e., the electrocaloric effect or ECE) [1] where an electric field perturbs the dipolar order and therefore the entropy of the system can enable solid-state cooling devices. [5,6] Key to such applications is the ability to manipulate and control the temperatureand field-dependence of polarization and entropic changes in ferroic materials. In turn, research has focused on finding pathways to enhance the pyroelectric π = ∂ Ferroelectric Thin FilmsThe complex interplay of polarization (P), temperature (T), entropy (S), and electric field (E) in ferroic materials enables electrothermal susceptibilities useful for a range of applications.

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Section: Thermophysical Properties (At 300 K) Of the Various Thin Filmentioning

confidence: 99%

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films

et al. 2018

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“…First, we use the Curie temperature (T C ) as an indicator of the influence of our heterostructure design on the ferroelectric properties of the BaTiO 3 membranes, since biaxial strain [25] and strontium content [26,54] are known to strongly affect T C . Using a thermodynamic model [55,56] we can predict the temperature dependence of the ferroelectric polarization for all membrane varieties studied herein (Figure 2a).…”

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confidence: 99%

Beyond Substrates: Strain Engineering of Ferroelectric Membranes

et al. 2020

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Integrating the diverse functionalities of complex oxides into semiconductor [1-7] and flexible [8-12] electronics is a major technological challenge that has motivated extensive work. But despite considerable effort, the structural, chemical, and thermal mismatches between such substrates and complex-oxide materials often yield films with considerably worse crystal quality than that attained on single-crystal perovskite substrates. Alternative strategies for hetero-integration via substrate release and transfer, mimicking the fabrication processes of van-der-Waals heterostructures, [13-15] are just now beginning to yield single-crystal oxide films on arbitrary substrates, [16-21] thus circumventing the constraints of epitaxial growth. Moreover, these detached films no longer experience mechanical constraint from the substrate, giving more flexibility in structural manipulation and heterostructure assembly. Strain control over the lattice structure is particularly impactful in ferroelectrics where the polarization is directly connected to structural distortions. [22,23] In thin films, strain can define the optimal operating temperature regime [24-26] or domain configuration [27-29] that will boost electro-mechanical or thermal functionalities, Strain engineering in perovskite oxides provides for dramatic control over material structure, phase, and properties, but is restricted by the discrete strain states produced by available high-quality substrates. Here, using the ferroelectric BaTiO 3 , production of precisely strain-engineered, substratereleased nanoscale membranes is demonstrated via an epitaxial lift-off process that allows the high crystalline quality of films grown on substrates to be replicated. In turn, fine structural tuning is achieved using interlayer stress in symmetric trilayer oxide-metal/ferroelectric/oxide-metal structures fabricated from the released membranes. In devices integrated on silicon, the interlayer stress provides deterministic control of ordering temperature (from 75 to 425 °C) and releasing the substrate clamping is shown to dramatically impact ferroelectric switching and domain dynamics (including reducing coercive fields to <10 kV cm −1 and improving switching times to <5 ns for a 20 µm diameter capacitor in a 100-nm-thick film). In devices integrated on flexible polymers, enhanced room-temperature dielectric permittivity with large mechanical tunability (a 90% change upon ±0.1% strain application) is demonstrated. This approach paves the way toward the fabrication of ultrafast CMOS-compatible ferroelectric memories and ultrasensitive flexible nanosensor devices, and it may also be leveraged for the stabilization of novel phases and functionalities not achievable via direct epitaxial growth. Perovskite ABO 3 oxides can display an immense number of phases and functions by merely changing the A-and B-site cations. Even within a single chemistry, multiple phases can be in competition, and their stability can be tuned statically by fixing The ORCID identification number(s) for the ...

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“…However, in the last few years HAADF-STEM has emerged as the preferred technique for mapping atomic polar displacements because the samples can be thicker, which helps to preserve the native domain structure, and the interpretation of the image contrast is straightforward and reliable [56,79,115,[132][133][134][135][136][137][138][139]. Mapping of atomic polar displacements from HAADF-STEM images was successfully applied to reveal various domain wall configurations [115,[132][133][134][135]140], flux-closure domain patterns [136], ferroelectric vortex domains [137,138], polarization gradients [56,141], as well as interface and surface reconstructions in ferroelectric thin films [142]; see Figure 16. In these examples, the ferroelectric films present the pseudocubic perovskite-type structure with general formula ABO 3, where A and B are cations of different size and O is the anion bonding to both.…”

Section: Ferroelectric Polarization Mapping From High-resolution Imagesmentioning

confidence: 99%

Probing local order in multiferroics by transmission electron microscopy

Campanini

Erni

Rossell

2019

Physical Sciences Reviews

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Abstract The ongoing trend toward miniaturization has led to an increased interest in the magnetoelectric effect, which could yield entirely new device concepts, such as electric field-controlled magnetic data storage. As a result, much work is being devoted to developing new robust room temperature (RT) multiferroic materials that combine ferromagnetism and ferroelectricity. However, the development of new multiferroic devices has proved unexpectedly challenging. Thus, a better understanding of the properties of multiferroic thin films and the relation with their microstructure is required to help drive multiferroic devices toward technological application. This review covers in a concise manner advanced analytical imaging methods based on (scanning) transmission electron microscopy which can potentially be used to characterize complex multiferroic materials. It consists of a first broad introduction to the topic followed by a section describing the so-called phase-contrast methods, which can be used to map the polar and magnetic order in magnetoelectric multiferroics at different spatial length scales down to atomic resolution. Section 3 is devoted to electron nanodiffraction methods. These methods allow measuring local strains, identifying crystal defects and determining crystal structures, and thus offer important possibilities for the detailed structural characterization of multiferroics in the ultrathin regime or inserted in multilayers or superlattice architectures. Thereafter, in Section 4, methods are discussed which allow for analyzing local strain, whereas in Section 5 methods are addressed which allow for measuring local polarization effects on a length scale of individual unit cells. Here, it is shown that the ferroelectric polarization can be indirectly determined from the atomic displacements measured in atomic resolution images. Finally, a brief outlook is given on newly established methods to probe the behavior of ferroelectric and magnetic domains and nanostructures during in situ heating/electrical biasing experiments. These in situ methods are just about at the launch of becoming increasingly popular, particularly in the field of magnetoelectric multiferroics, and shall contribute significantly to understanding the relationship between the domain dynamics of multiferroics and the specific microstructure of the films providing important guidance to design new devices and to predict and mitigate failures.

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Large polarization gradients and temperature-stable responses in compositionally-graded ferroelectrics

Cited by 71 publications

References 54 publications

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films

Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films

Beyond Substrates: Strain Engineering of Ferroelectric Membranes

Probing local order in multiferroics by transmission electron microscopy

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