Nonvolatile Ferroelastic Strain from Flexoelectric Internal Bias Engineering

Hou, Wenhui; Chowdhury, Shoieb Ahmed; Dey, Aditya; Watson, Carla; Peña, Tara; Azizimanesh, Ahmad; Askari, Hesam; Wu, Stephen M.

doi:10.1103/physrevapplied.17.024013

Cited by 10 publications

(7 citation statements)

References 87 publications

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“…Considering possible existence of multiple sub-coercive electric states, the single domain state with the accompanied remanent tension along the polarization direction can be favourable for larger PV response in a poled direction. Taking into account that internal bias field giving rise to opposite remanent stresses can be also formed by growth conditions, thermal/electrical [76,77] history or doping [78], our results on the well-controlled model material can explain differences or lack of reproducibility in the literature. Regardless the way of stress introduction: either material fabrication [79,80] or post-processing techniques, the strain engineering can be considered as a key enabling strategy for tuning and optimizing PV properties in FEs.…”

Section: Discussionmentioning

confidence: 81%

On the photovoltaic effect asymmetry in ferroelectrics

Semak¹,

Kapustianyk²,

Eliyashevskyy³

et al. 2022

J. Phys.: Condens. Matter

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Despite symmetrical polarization, the magnitude of a light-induced voltage is known to be asymmetric with respect to poling sign in many photovoltaic (PV) ferroelectrics (FEs). This asymmetry remains unclear and is often attributed to extrinsic effects. We show here for the first time that such an asymmetry can be intrinsic, steaming from the superposition of asymmetries of internal FE bias and electro-piezo-strictive deformation. This hypothesis is confirmed by the observed decrease of PV asymmetry for smaller FE bias. Moreover, the both PV effect and remanent polarization are found to increase under vacuum-induced expansion and to decrease for gas-induced compression, with tens percents tunability. The change in cations positions under pressure is analysed through the first-principle density functional theory calculations. The reported properties provide key insight for FE-based solar elements optimization.

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Section: Discussionmentioning

confidence: 81%

On the photovoltaic effect asymmetry in ferroelectrics

Semak¹,

Kapustianyk²,

Eliyashevskyy³

et al. 2022

J. Phys.: Condens. Matter

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“…We use the framework of generalized gradient approximation (GGA) , embodied in the Quantum Espresso open-source package for conducting this calculation. The GGA, along with the Perdew–Burke–Ernzerhof (PBE) form, serves as the exchange-correlation functional with ultrasoft pseudopotentials. , We account for the van der Waals interaction using the semiempirical Grimme functional (DFT-D2 (Grimme-D2)), also employed in earlier works. − The wave functions are expanded by using a plane wave basis set with a kinetic energy cutoff of 40 Ry (544 eV) and an energy cutoff of 450 Ry (6123 eV) for charge density (and the self-consistent field potential). It is important to note that the energy cutoff defines the maximum energy for the plane wave basis set, ensuring that the basis set contains sufficient wave functions to accurately describe the electronic structure of the system.…”

Section: Methodsmentioning

confidence: 99%

“… 41 , 42 We account for the van der Waals interaction using the semiempirical Grimme functional (DFT-D2 (Grimme-D2)), 43 also employed in earlier works. 44 − 47 The wave functions are expanded by using a plane wave basis set with a kinetic energy cutoff of 40 Ry (544 eV) and an energy cutoff of 450 Ry (6123 eV) for charge density (and the self-consistent field potential). It is important to note that the energy cutoff defines the maximum energy for the plane wave basis set, ensuring that the basis set contains sufficient wave functions to accurately describe the electronic structure of the system.…”

Section: Methodsmentioning

confidence: 99%

Uniaxial Strain-Induced Stacking Order Change in Trilayer Graphene

Dey,

Azizimanesh,

et al. 2024

ACS Appl. Mater. Interfaces

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The layer stacking order in two-dimensional heterostructures, like graphene, affects their physical properties and potential applications. Trilayer graphene, specifically ABCtrilayer graphene, has captured significant interest due to its potential for correlated electronic states. However, achieving a stable ABC arrangement is challenging due to its lower thermodynamic stability compared to the more stable ABA stacking. Despite recent advancements in obtaining ABC graphene through external perturbations, such as strain, the stacking transition mechanism remains insufficiently explored. In this study, we unveil a universal mechanism to achieve ABC stacking, applicable for understanding ABA to ABC stacking changes induced by any mechanical perturbations. Our approach is based on a novel strain engineering technique that induces interlayer slippage and results in the formation of stable ABC domains. We investigate the underlying interfacial mechanisms of this stacking change through computational simulations and experiments. Our findings demonstrate a highly anisotropic and significant transformation of ABA stacking to large and stable ABC domains facilitated by interlayer slippage. Through atomistic simulations and local energy analysis, we systematically demonstrate the mechanism for this stacking transition, that is dependent on specific loading orientation. Understanding such a mechanism allows this material system to be engineered by design compatible with industrial techniques on a device-by-device level. We conduct Raman studies to validate and characterize the formed ABC stacking, highlighting its distinct features compared to the ABA region. Our results contribute to a clearer understanding of the stacking change mechanism and provide a robust and controllable method for achieving stable ABC domains, facilitating their use in developing advanced optoelectronic devices.

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“…The real space lattices of TBG systems were constructed using the ATOMISTIX TOOLKIT (QuantumATK) package . All the first-principles simulations were conducted with generalized gradient approximation (GGA) assimilated in the Quantum Espresso open source package. , The Perdew–Burke–Ernzerhof (PBE) form and GGA have been used as the exchange-correlation functional .…”

Section: Methodsmentioning

confidence: 99%

An Atomistic Insight into Moiré Reconstruction in Twisted Bilayer Graphene beyond the Magic Angle

Dey

Chowdhury

Peña

et al. 2023

ACS Appl. Eng. Mater.

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Twisted bilayer graphene exhibits electronic properties strongly correlated with the size and arrangement of moiré patterns. While rigid rotation of the two graphene layers results in a moiré interference pattern, local rearrangements of atoms due to interlayer van der Waals interactions result in atomic reconstruction within the moiré cells. Manipulating these patterns by controlling the twist angle and externally applied strain provides a promising route to tuning their properties. Atomic reconstruction has been extensively studied for angles close to or smaller than the magic angle (θ m = 1.1°). However, this effect has not been explored for applied strain and is believed to be negligible for high twist angles. Using interpretive and fundamental physical measurements, we use theoretical and numerical analyses to resolve atomic reconstruction in angles above θ m . In addition, we propose a method to identify local regions within moiré cells and track their evolution with strain for a range of representative high twist angles. Our results show that atomic reconstruction is actively present beyond the magic angle, and its contribution to the moiré cell evolution is significant. Our theoretical method to correlate local and global phonon behavior further validates the role of reconstruction at higher angles. Our findings provide a better understanding of moiré reconstruction in large twist angles and the evolution of moiré cells under the application of strain, which might be potentially crucial for twistronics-based applications.

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Nonvolatile Ferroelastic Strain from Flexoelectric Internal Bias Engineering

Cited by 10 publications

References 87 publications

On the photovoltaic effect asymmetry in ferroelectrics

On the photovoltaic effect asymmetry in ferroelectrics

Uniaxial Strain-Induced Stacking Order Change in Trilayer Graphene

An Atomistic Insight into Moiré Reconstruction in Twisted Bilayer Graphene beyond the Magic Angle

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