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S Prokhorenko, Y Nahas, L Bellaiche
Homotopy theory and first-principles-based effective Hamiltonian simulations are combined to investigate the stability of topological defects in proper ferroelectric crystals. We show that, despite a nearly trivial topology of the order parameter space, these materials can exhibit stable topological point defects in their tetragonal polar phase and stable topological line defects in their orthorhombic polar phase. The stability of such defects originates from a novel mechanism of topological protection related to finite-temperature fluctuations of local dipoles...
April 7, 2017: Physical Review Letters
Ezequiel E Ferrero, Laura Foini, Thierry Giamarchi, Alejandro B Kolton, Alberto Rosso
In the presence of impurities, ferromagnetic and ferroelectric domain walls slide only above a finite external field. Close to this depinning threshold, they proceed by large and abrupt jumps called avalanches, while, at much smaller fields, these interfaces creep by thermal activation. In this Letter, we develop a novel numerical technique that captures the ultraslow creep regime over huge time scales. We point out the existence of activated events that involve collective reorganizations similar to avalanches, but, at variance with them, display correlated spatiotemporal patterns that resemble the complex sequence of aftershocks observed after a large earthquake...
April 7, 2017: Physical Review Letters
Ignasi Fina, Alberto Quintana, Jessica Padilla-Pantoja, Xavier Marti, Ferran Macià, Florencio Sanchez, Michael Foerster, Lucia Aballe, Josep Fontcuberta, Jordi Sort
Steady or dynamic magnetoelectric response, selectable and adjustable by only varying the amplitude of an applied electric field, is found in a multiferroic FeRh/PMNPT device. In-operando time-dependent structural, ferroelectric and magnetoelectric characterizations provide evidence that, as in magnetic shape-memory martensitic alloys, the observed distinctive magnetoelectric responses are related to the time-dependent relative abundance of antiferromagnetic-ferromagnetic phases in FeRh, unbalanced by voltage-controlled strain...
April 21, 2017: ACS Applied Materials & Interfaces
N Andreeva, M Tomkovich, A Naberezhnov, B Nacke, A Filimonov, O Alekseeva, P Vanina, V Nizhankovskii
The morphology and composition of four types of two-phase alkali borosilicate glasses with magnetic atoms prepared by inductive melting have been studied. The results of scanning electron microscopy point to uniform distribution of Na, Si, and O atoms in these samples while magnetic iron atoms form ball-shaped agglomerates. The magnetic properties of these agglomerates have been confirmed by magnetic force microscopy. Atomic force microscopy had shown that in these samples two different morphological structures, drop-like and dendrite net, are formed...
2017: TheScientificWorldJournal
Cheng-Min Ji, Zhihua Sun, Aurang Zeb, Sijie Liu, Jing Zhang, Maochun Hong, Junhua Luo
Perovskite hybrids (e.g. CH3NH3PbI3) are holding great promise in photovoltaics and optoelectronics, due to their remarkable semiconducting property and potential ferroelectricity. However, up to date it still lacks conclusive evidence for the bulk ferroelectricity of CH3NH3PbI3. In this context, it is highly desirable to assemble concrete perovskite ferroelectric hybrids with the semiconducting feature. Here we report, for the first time, a class of lead-free perovskite halides, (N-methylpyrrolidinium)3Sb2Cl9-9xBr9x (x = 0-1), showing large ferroelectric polarization (5...
April 20, 2017: Journal of Physical Chemistry Letters
Joao Vidal, Andrey V Turutin, Ilya V Kubasov, Mikhail D Malinkovich, Yurii N Parkhomenko, Svetlana P Kobeleva, Andrei L Kholkin, Nikolai A Sobolev
The anisotropic direct magnetoelectric (ME) properties of bi-layered composites comprising magnetostrictive metglas foils and single-crystalline piezoelectric bidomain plates of 127ºY-cut LiNbO<sub>3<sub> (LNO) have been studied theoretically and experimentally. The LNO plates possessed an engineered ferroelectric macrobidomain structure with opposite spontaneous polarization vectors. Impedance, ME effect and equivalent magnetic noise density measurements have been performed under quasi-static and resonant conditions...
April 13, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Chunli Jiang, Ni Zhong, Chunhua Luo, Hechun Lin, Yuanyuan Zhang, Hui Peng, Chun-Gang Duan
Combination of excellent optical properties and ferroelectricity of hybrid materials leads to high-performance optoelectronic devices. Here we present a new organic-inorganic hybrid compound (diisopropylammonium)2MnBr4 (DIPA2MnBr4) which shows high temperature ferroelectricity accompanied by highly efficient green-light emission. DIPA2MnBr4 also exhibits sensitive and selective optical response to alcohol vapors.
April 19, 2017: Chemical Communications: Chem Comm
Tieren Gao, Xiaohang Zhang, William Ratcliff, Shingo Maruyama, Makoto Murakami, Anbusathaiah Varatharajan, Zahra Yamani, Peijie Chen, Ke Wang, Huairuo Zhang, Robert Shull, Leonid A Bendersky, John Unguris, Ramamoorthy Ramesh, Ichiro Takeuchi
Electric-field (E-field) control of magnetism enabled by multiferroic materials has the potential to revolutionize the landscape of present memory devices plagued with high energy dissipation. To date, this E-field controlled multiferroic scheme has only been demonstrated at room temperature using BiFeO3 films grown on DyScO3, a unique and expensive substrate, which gives rise to a particular ferroelectric domain pattern in BiFeO3. Here, we demonstrate reversible electric-field-induced switching of the magnetic state of the Co layer in Co/BiFeO3 (BFO) (001) thin film heterostructures fabricated on (001) SrTiO3 (STO) substrates...
April 20, 2017: Nano Letters
Yannan Shen, P G Kevrekidis, G P Veldes, D J Frantzeskakis, D DiMarzio, X Lan, V Radisic
In the present work, we explore soliton and roguelike wave solutions in the transmission line analog of a nonlinear left-handed metamaterial. The nonlinearity is expressed through a voltage-dependent, symmetric capacitance motivated by recently developed ferroelectric barium strontium titanate thin-film capacitor designs. We develop both the corresponding nonlinear dynamical lattice and its reduction via a multiple scales expansion to a nonlinear Schrödinger (NLS) model for the envelope of a given carrier wave...
March 2017: Physical Review. E
Vladimir V Kesaev, Alexei D Kiselev, Evgeny P Pozhidaev
We study the electro-optic properties of subwavelength-pitch deformed-helix ferroelectric liquid crystals (DHFLC) illuminated with unpolarized light. In the experimental setup based on the Mach-Zehnder interferometer, it was observed that the reference and the sample beams being both unpolarized produce the interference pattern which is insensitive to rotation of in-plane optical axes of the DHFLC cell. We find that the field-induced shift of the interference fringes can be described in terms of the electrically dependent Pancharatnam relative phase determined by the averaged phase shift, whereas the visibility of the fringes is solely dictated by the phase retardation...
March 2017: Physical Review. E
Zhengyuan Tu, Menghao Wu, Xiao Cheng Zeng
Coexistence of ferromagnetism and ferroelectricity in a single 2D material is highly desirable for integration of multi-functional units in 2D material-based circuits. Herein, we report theoretical evidence of C6N8H organic network as being the first 2D organic multiferroic material with coexisting FM and FE properties. The ferroelectricity stems from multi-mode proton-transfer within the 2D C6N8H network, in which a long-range proton-transfer mode is enabled by the facilitation of oxygen molecule when the network is exposed to the air...
April 15, 2017: Journal of Physical Chemistry Letters
Yu Qiao, Yanfeng Zhou, Shan Wang, Long Yuan, Yanyan Du, Dayong Lu, Guangbo Che, Huinan Che
The hydrothermal synthesis and magnetic, dielectric and ferroelectric property characterization of ABO3-perovskite GdFe1-xCrxO3 (0 < x < 1) are reported. The mineralizer KOH plays a critical role in the perovskite structure of the sample. The Fe/Cr ratio of the final crystal is controlled by the alkalinity in the initial reaction mixtures. The lattice parameters and magnetic ordering transition temperature have a close relationship with the Fe/Cr ratio. The temperature dependent magnetic properties of GdFe1-xCrxO3 (0 < x < 1) samples show a close relationship with substituent ratios of Cr(3+)...
April 13, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Salvatore A Pullano, Ifana Mahbub, Syed K Islam, Antonino S Fiorillo
This paper presents a ferroelectric polymer-based temperature sensor designed for microfluidic devices. The integration of the sensor into a system-on-a-chip platform facilitates quick monitoring of localized temperature of a biological fluid, avoiding errors in the evaluation of thermal evolution of the fluid during analysis. The contact temperature sensor is fabricated by combining a thin pyroelectric film together with an infrared source, which stimulates the active element located on the top of the microfluidic channel...
April 13, 2017: Sensors
Wei-Jian Xu, Peng-Fei Li, Yuan-Yuan Tang, Wei-Xiong Zhang, Ren-Gen Xiong, Xiao-Ming Chen
The underlying phase transitions of ferroelectric mechanisms in molecular crystals are mainly limited in order-disorder and displacive types that are not involved in breaking of the chemical bonds. Here, we show that the bond-switching transition under ambient pressure is designable in molecular crystals, and demonstrate how to utilize the weaker and switchable coordination bonds in a novel molecular perovskite, [(CH3)3NOH]2[KFe(CN)6] (TMC-1), to afford a scarce multi-axial ferroelectrics with a high Curie temperature of 402 K and 24 equivalent ferroelectric directions (more than that of BaTiO3)...
April 12, 2017: Journal of the American Chemical Society
Pavan Nukala, Mingliang Ren, Rahul Agarwal, Jacob Berger, Gerui Liu, A T Charlie Johnson, Ritesh Agarwal
Germanium telluride (GeTe) is both polar and metallic, an unusual combination of properties in any material system. The large concentration of free-carriers in GeTe precludes the coupling of external electric field with internal polarization, rendering it ineffective for conventional ferroelectric applications and polarization switching. Here we investigate alternate ways of coupling the polar domains in GeTe to external electrical stimuli through optical second harmonic generation polarimetry and in situ TEM electrical testing on single-crystalline GeTe nanowires...
April 12, 2017: Nature Communications
Vishal Boddu, Florian Endres, Paul Steinmann
Ferroelectric materials contain domains of ordered electric dipoles, separated by domain walls, that can undergo polarisation switching under externally applied electric fields. The domain switching dynamics in ferroelectric materials plays an essential role in their application to electronic and electro-optic de- vices. Previous studies suggest that the switching occurs largely through domain wall motion which is explained from the viewpoint of statistical physics on surface growth as the behaviour of a pinned elas- tic interface...
April 11, 2017: Scientific Reports
Torsten Trittel, Kirsten Harth, Ralf Stannarius
The tilt angle of smectic C phases can be controlled by external forces of very different nature. In particular near a smectic A-smectic C transition, it is susceptible to temperature changes. It can be influenced with electric fields (electroclinic effect), and even mechanically by intra-layer stresses in elastomers. We show that capillary forces that act during the rupture of a free-standing smectic C film can trigger a smectic C to smectic A transition, which rapidly reduces the surface area of the films, concurrently increasing the film thickness...
April 11, 2017: Soft Matter
J P B Silva, F L Faita, K Kamakshi, K C Sekhar, J Agostinho Moreira, A Almeida, M Pereira, A A Pasa, M J M Gomes
An enhanced resistive switching (RS) effect is observed in Pt/BaTiO3(BTO)/ITO ferroelectric structures when a thin HfO2:Al2O3 (HAO) dielectric layer is inserted between Pt and BTO. The P-E hysteresis loops reveal the ferroelectric nature of both Pt/BTO/ITO and Pt/HAO/BTO/ITO structures. The relation between the RS and the polarization reversal is investigated at various temperatures in the Pt/HAO/BTO/ITO structure. It is found that the polarization reversal induces a barrier variation in the Pt/HAO/BTO interface and causes enhanced RS, which is suppressed at Curie temperature (Tc = 140 °C)...
April 11, 2017: Scientific Reports
Gabriel Sanchez-Santolino, Javier Tornos, David Hernandez-Martin, Juan I Beltran, Carmen Munuera, Mariona Cabero, Ana Perez-Muñoz, Jesus Ricote, Federico Mompean, Mar Garcia-Hernandez, Zouhair Sefrioui, Carlos Leon, Steve J Pennycook, Maria Carmen Muñoz, Maria Varela, Jacobo Santamaria
The peculiar features of domain walls observed in ferroelectrics make them promising active elements for next-generation non-volatile memories, logic gates and energy-harvesting devices. Although extensive research activity has been devoted recently to making full use of this technological potential, concrete realizations of working nanodevices exploiting these functional properties are yet to be demonstrated. Here, we fabricate a multiferroic tunnel junction based on ferromagnetic La0.7Sr0.3MnO3 electrodes separated by an ultrathin ferroelectric BaTiO3 tunnel barrier, where a head-to-head domain wall is constrained...
April 10, 2017: Nature Nanotechnology
Evgeny Y Tsymbal, Julian P Velev
No abstract text is available yet for this article.
April 10, 2017: Nature Nanotechnology
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