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Ming-Cheng Kao, Hone-Zern Chen, San-Lin Young, Kai-Huang Chen, Jung-Lung Chiang, Jen-Bin Shi
Bi0.8Pr0.2Fe0.95Mn0.05O₃/Bi3.96Gd0.04Ti2.95W0.05O12 (BPFMO/BGTWO) bilayer thin films with Multiferroic/Ferroelectric (MF/FE) structures were deposited onto Pt(111)/Ti/SiO₂/Si(100) substrates by using the sol-gel method with rapid thermal annealing. The BPFMO/BGTWO thin films exhibited well-saturated ferromagnetic and ferroelectric hysteresis loops because of the electro-magnetic coupling induced by the MF/FE structure. The remnant magnetization (2Mr) and remnant polarization (2Pr) were 4.6 emu/cm³ and 62 μC/cm², respectively...
November 20, 2017: Materials
Andrei Nikitchenko, Andrei V Azovtsev, Nikolay A Pertsev
Ferroelectric crystallites embedded into a dielectric matrix experience temperature-dependent elastic strains caused by differences in the thermal expansion of the crystallites and the matrix. Owing to the electrostriction, these lattice strains may affect polarization states of ferroelectric inclusions significantly, making them different from those of a stress-free bulk crystal. Here, using a nonlinear thermodynamic theory, we study the mechanical effect of elastic matrix on the phase states of embedded single-domain ferroelectric nanocrystals...
November 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jian-Qing Dai, Xiao-Ya Li, Jie-Wang Xu
For graphene/ferroelectric hybrid structures, the atomistic and electronic details of the interfaces are of crucial importance for charge doping in graphene. In this paper, we choose thermodynamically stable BiFeO3(0001) surfaces to explore the adsorption behavior and charge doping effect in a graphene/BiFeO3 system. By performing first-principles calculations, we find that both the adsorption behavior and charge doping effect show distinct characteristics for graphene adsorbed on the oppositely polarized BiFeO3(0001) surfaces...
November 20, 2017: Physical Chemistry Chemical Physics: PCCP
Alexander Ruff, Alois Loidl, Stephan Krohns
Multiferroics, showing both ferroelectric and magnetic order, are promising candidates for future electronic devices. Especially, the fundamental understanding of ferroelectric switching is of key relevance for further improvements, which however is rarely reported in literature. On a prime example for a spin-driven multiferroic, LiCuVO₄, we present an extensive study of the ferroelectric order and the switching behavior as functions of external electric and magnetic fields. From frequency-dependent polarization switching and using the Ishibashi-Orihara theory, we deduce the existence of ferroelectric domains and domain-walls...
November 17, 2017: Materials
Leonid L Rusevich, Guntars Zvejnieks, Alessandro Erba, Roberto Dovesi, Eugene E Kotomin
An enhancement of the piezoelectric properties of lead-free materials, which allow conversion of mechanical energy into electricity, is a task of great importance and interest. Results of first-principles calculations of piezoelectric/electromechanical properties of the Ba(1-x)SrxTiO3 (BSTO) ferroelectric solid solution with perovskite structure are presented and discussed. Calculations are performed within the linear combination of atomic orbitals (LCAO) approximation and periodic-boundary conditions, using advanced hybrid functionals of the density-functional-theory (DFT)...
November 17, 2017: Journal of Physical Chemistry. A
W Saenrang, B A Davidson, F Maccherozzi, J P Podkaminer, J Irwin, R D Johnson, J W Freeland, J Íñiguez, J L Schad, K Reierson, J C Frederick, C A F Vaz, L Howald, T H Kim, S Ryu, M V Veenendaal, P G Radaelli, S S Dhesi, M S Rzchowski, C B Eom
Exploiting multiferroic BiFeO3 thin films in spintronic devices requires deterministic and robust control of both internal magnetoelectric coupling in BiFeO3, as well as exchange coupling of its antiferromagnetic order to a ferromagnetic overlayer. Previous reports utilized approaches based on multi-step ferroelectric switching with multiple ferroelectric domains. Because domain walls can be responsible for fatigue, contain localized charges intrinsically or via defects, and present problems for device reproducibility and scaling, an alternative approach using a monodomain magnetoelectric state with single-step switching is desirable...
November 17, 2017: Nature Communications
Wei-Qiang Liao, Yuan-Yuan Tang, Peng-Fei Li, Yu-Meng You, Ren-Gen Xiong
Piezoelectric materials have been widely used in various applications, such as high-voltage sources, actuators, sensors, motors, fre-quency standard, vibration reducer, and so on. In the past decades, lead zirconate titanate (PZT) binary ferroelectric ceramics have dominated the commercial piezoelectric market due to their excellent properties near the morphotropic phase boundary (MPB), although they contain more than 60% toxic lead element. Here, we report a lead-free and one-composition molecular ferroelectric trimethylbromomethylammonium tribromomanganese (ΙΙ) (TMBM-MnBr3) with a large piezoelectric coefficient d33 of 112 pC/N along polar axis, comparable with those of typically one-composition piezoceramics such as BaTiO3 along polar axis [001] (~90 pC/N) and much greater than those of most known molecular ferroelectrics (almost below 40 pC/N)...
November 16, 2017: Journal of the American Chemical Society
I Levin, V Krayzman, G Cibin, M G Tucker, M Eremenko, K Chapman, R L Paul
Perovskite potassium sodium niobates, K1-xNaxNbO3, are promising lead-free piezoelectrics. Their dielectric and piezoelectric characteristics peak near x = 0.5, but the reasons for such property enhancement remain unclear. We addressed this uncertainty by analyzing changes in the local and average structures across the x = 0.5 composition, which have been determined using simultaneous Reverse Monte Carlo fitting of neutron and X-ray total-scattering data, potassium EXAFS, and diffuse-scattering patterns in electron diffraction...
November 15, 2017: Scientific Reports
Wenxiu Gao, Zhuolei Zhang, Peng-Fei Li, Yuan-Yuan Tang, Ren-Gen Xiong, Guoliang Yuan, Shenqiang Ren
Multifunctional properties of chiral molecules arise from the coexistence of mirror-symmetry-induced stereoisomers and optical rotation characteristics in one material. One of these complex phenomena in these molecules is chiral ferroelectricity, providing the coupling between polarized light and the spatial asymmetry induced dipole moment. Herein we describe the chiral polarization and electroresistance in molecular ferroelectric (R)-(-)-3-hydroxyquinuclidinium chloride thin films with a Curie temperature of 340 K...
November 15, 2017: ACS Nano
Owoong Kwon, Daehee Seol, Dongkyu Lee, Hee Han, Ionela Lindfors-Vrejoiu, Woo Lee, Stephen Jesse, Ho Nyung Lee, Sergei V Kalinin, Marin Alexe, Yunseok Kim
Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. Accordingly, to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio...
November 14, 2017: Advanced Materials
Yan Chen, Yang Zhang, Robert Keil, Michael Zopf, Fei Ding, Oliver G Schmidt
Coercive fields of piezoelectric materials can be strongly influenced by environmental temperature. We investigate this influence using a heterostructure consisting of a single crystal piezoelectric film and a quantum dots containing membrane. Applying electric field leads to a physical deformation of the piezoelectric film, thereby inducing strain in the quantum dots and thus modifying their optical properties. The wavelength of the quantum dot emission shows butterfly-like loops, from which the coercive fields are directly derived...
November 15, 2017: Nano Letters
Sanghamitra Mukhopadhyay, Matthias J Gutmann, Mónica Jiménez-Ruiz, Dominik B Jochym, Kjartan T Wikfeldt, Keith Refson, Felix Fernandez-Alonso
A detailed study of the thermal behaviour of atomic motions in the organic ferroelectric croconic acid is presented in the temperature range 5-300 K. Using high-resolution inelastic neutron scattering and first-principles electronic-structure calculations within the framework of density functional theory and a quasiharmonic phonon description of the material, we find that the frequencies of the well defined doublet in inelastic neutron scattering spectra associated with out-of-plane motions of hydrogen-bonded protons decrease monotonically with temperature indicating weakening of these bonding motifs and enhancement of proton motions...
November 13, 2017: Physical Chemistry Chemical Physics: PCCP
Rajasekaran Ganeshkumar, Suhas Somnath, Chin Wei Cheah, Stephen Jesse, Sergei V Kalinin, Rong Zhao
Ferroelectric perovskites are an important group of materials underpinning a wide variety of devices ranging from sensors and transducers to non-volatile memories and photovoltaic cells. Despite the progress in material synthesis, ferroelectric characterization of nanoscale perovskites is still a challenge. Piezoresponse force microscopy (PFM) is one of the most popular tools for probing and manipulating nanostructures to study the ferroelectric properties. However, the interpretation of hysteresis data and alternate signal origins are critical...
November 13, 2017: ACS Applied Materials & Interfaces
Simon Hausmann, Jingfan Ye, Toshihiro Aoki, Jian-Guo Zheng, Jochen Stahn, Francis Bern, Binda Chen, Carmine Autieri, Biplab Sanyal, Pablo D Esquinazi, Peter Böni, Amitesh Paul
A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.
November 10, 2017: Scientific Reports
Sergey V Ptashnik, Anatoliy K Mikhailov, Alexander V Yastrebov, Peter K Petrov, Wei Liu, Neil McN Alford, Soeren Hirsch, Andrey B Kozyrev
Design principles of a new class of microwave thin film bulk acoustic resonators with multiband resonance frequency switching ability are presented. The theory of the excitation of acoustic eigenmodes in multilayer ferroelectric structures is considered, and the principle of selectivity for resonator with an arbitrary number of ferroelectric layers is formulated. A so called "criterion function" is suggested that allows to determine the conditions for effective excitation at one selected resonance mode with suppression of other modes...
November 10, 2017: Scientific Reports
Gabriele De Luca, Nives Strkalj, Sebastian Manz, Corinne Bouillet, Manfred Fiebig, Morgan Trassin
The success of oxide electronics depends on the ability to design functional properties such as ferroelectricity with atomic accuracy. However, despite tremendous advances in ferroelectric heterostructures, the development towards multilevel architectures with precise layer-by-layer command over the polarization is impeded by the lack of continuous control over the balance of electrostatics, strain, chemistry and film thickness during growth. Moreover, the polarization in the deeper layers becomes inaccessible when these are buried by the ongoing deposition...
November 10, 2017: Nature Communications
Ying Liu, Yujia Wang, Yinlian Zhu, Chihou Lei, Yunlong Tang, Shuang Li, Sirui Zhang, J Y Li, Xiuliang Ma
Ferroelectric flux-closures are very promising in high-density storage and other nanoscale electronic devices. To make the data bits addressable, the nanoscale flux-closures are required to be periodic via a controlled growth. Although flux-closure quadrant arrays with 180o domain walls perpendicular to the interfaces (V-closure) have been observed in strained ferroelectric PbTiO3 films, the flux-closure quadrants therein are rather asymmetric. In this work, we report not only a periodic array of the symmetric flux-closure quadrants with 180o domain walls parallel to the interfaces (H-closure), but also a large scale alternative stacking of the V- and H-closure arrays in PbTiO3/SrTiO3 multilayers...
November 10, 2017: Nano Letters
Yu-Hua Meng, Wei Bai, Heng Gao, Shi-Jing Gong, Ji-Qing Wang, Chun-Gang Duan, Jun-Hao Chu
GeTe is a prototypical compound of a new class of multifunctional materials, i.e., ferroelectric Rashba semiconductors (FRS). In the present work, by combining the first-principles calculations and Rashba model analysis, we reexamine Rashba spin-orbit coupling (SOC) in a GeTe(111) crystal and clarify its linear Rashba SOC strength. We further investigate Rashba SOC at the interface of a GeTe(111)/InP(111) superlattice and demonstrate the ferroelectric manipulation of Rashba SOC in detail. A large modulation of Rashba SOC is obtained, and surprisingly, we find that Rashba SOC does not monotonically increase with the increase of ferroelectric displacement, due to the parabola opening reversal of Rashba splitting bands...
November 10, 2017: Nanoscale
Eva D Korblova, Edward Guzman, Joseph E Maclennan, Matthew A Glaser, Renfan Shao, Edgardo Garcia, Yongqiang Shen, Rayshan Visvanathan, Noel A Clark, David M Walba
We have previously reported the first realization of an orthogonal ferroelectric bent-core SmAPF phase by directed design in mesogens with a single tricarbosilane-terminated alkoxy tail. Given the potentially useful electrooptic properties of this phase, including analog phase-only electrooptic index modulation with optical latching, we have been exploring its "structure space", searching for novel SmAPF mesogens. Here, we report two classes of these-the first designed to optimize the dynamic range of the index modulation in parallel-aligned cells by lowering the bend angle of the rigid core, and the second expanding the structure space of the phase by replacing the tricarbosilane-terminated alkyl tail with a polyfluorinated polyethylene glycol oligomer...
November 9, 2017: Materials
Yu Jin Kim, Hyeon Woo Park, Seung Dam Hyun, Han Joon Kim, Keum Do Kim, Young Hwan Lee, Taehwan Moon, Yong Bin Lee, Min Hyuk Park, Cheol Seong Hwang
Ferroelectric (FE) capacitor is a critical electric component in microelectronic devices. Among many of its intriguing properties, the recent finding of voltage drop (V-drop) across the FE capacitor while the positive charges flow in is especially eye-catching. This finding was claimed to be direct evidence that the FE capacitor is in negative capacitance (NC) state, which must be useful for (infinitely) high capacitance and ultralow voltage operation of field-effect transistors. Nonetheless, the NC state corresponds to the maximum energy state of the FE material, so it has been widely accepted in the community that the material alleviates that state by forming ferroelectric domains...
November 8, 2017: Nano Letters
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