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Conroy MS, O'Connell E, Moore K, Jones L, Ramasse Q, Griffin S, Ophus C. Probing the Atomic-Scale Internal Phases with the Electron Beam of Mutliferroic Domain Walls Formed During Dynamics. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1363. [PMID: 37613704 DOI: 10.1093/micmic/ozad067.699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Michele Shelly Conroy
- Department of Materials, London Centre of Nanotechnology, Henry Royce Institute, Imperial College London, UK
| | - Eoghan O'Connell
- Max Planck Institute for the Science of Light, Erlangen, Germany
| | | | - Lewys Jones
- School of Physics, Advanced Microscopy Laboratory, Trinity College Dublin, Dublin, Ireland
| | - Quentin Ramasse
- SuperSTEM, SciTech Daresbury Science & Innovation Campus, & University of Leeds, UK
| | - Sinead Griffin
- Molecular Foundry Lawrence Berkeley National Laboratory, USA
| | - Colin Ophus
- Molecular Foundry Lawrence Berkeley National Laboratory, USA
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, USA
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Behera P, Parsonnet E, Gómez-Ortiz F, Srikrishna V, Meisenheimer P, Susarla S, Kavle P, Caretta L, Wu Y, Tian Z, Fernandez A, Martin LW, Das S, Junquera J, Hong Z, Ramesh R. Emergent Ferroelectric Switching Behavior from Polar Vortex Lattice. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208367. [PMID: 36930962 DOI: 10.1002/adma.202208367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 03/08/2023] [Indexed: 06/09/2023]
Abstract
Topologically protected polar textures have provided a rich playground for the exploration of novel, emergent phenomena. Recent discoveries indicate that ferroelectric vortices and skyrmions not only host properties markedly different from traditional ferroelectrics, but also that these properties can be harnessed for unique memory devices. Using a combination of capacitor-based capacitance measurements and computational models, it is demonstrated that polar vortices in dielectric-ferroelectric-dielectric trilayers exhibit classical ferroelectric bi-stability together with the existence of low-field metastable polarization states. This behavior is directly tied to the in-plane vortex ordering, and it is shown that it can be used as a new method of non-destructive readout-out of the poled state.
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Affiliation(s)
- Piush Behera
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Eric Parsonnet
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Fernando Gómez-Ortiz
- Department of Earth Sciences and Condensed Matter Physics, Universidad de Cantabria, Cantabria Campus Internacional, 39005, Santander, Spain
| | - Vishantak Srikrishna
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Peter Meisenheimer
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Sandhya Susarla
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Pravin Kavle
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Yongjun Wu
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, 310027, Hangzhou, China
| | - Zishen Tian
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Abel Fernandez
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Lane W Martin
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sujit Das
- Materials Research Centre, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Javier Junquera
- Department of Earth Sciences and Condensed Matter Physics, Universidad de Cantabria, Cantabria Campus Internacional, 39005, Santander, Spain
| | - Zijian Hong
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, 310027, Hangzhou, China
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California Berkeley, Berkeley, CA, 94720, USA
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Sokolikova MS, Cheng G, Och M, Palczynski P, El Hajraoui K, Ramasse QM, Mattevi C. Tuning the 1T'/2H phases in W xMo 1-xSe 2 nanosheets. NANOSCALE 2023; 15:2714-2725. [PMID: 36651927 PMCID: PMC9909680 DOI: 10.1039/d2nr05631c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Controlling materials' morphology, crystal phase and chemical composition at the atomic scale has become central in materials research. Wet chemistry approaches have great potential in directing the material crystallisation process to achieve tuneable chemical compositions as well as to target specific crystal phases. Herein, we report the compositional and crystal phase tuneability achieved in the quasi-binary WxMo1-xSe2 system with chemical and crystal phase mixing down to the atomic level. A series of WxMo1-xSe2 solid solutions in the form of nanoflowers with atomically thin petals were obtained via a direct colloidal reaction by systematically varying the ratios of transition metal precursors. We investigate the effect of selenium precursor on the morphology of the WxMo1-xSe2 material and show how using elemental selenium can enable the formation of larger and distinct nanoflowers. While the synthesised materials are compositionally homogeneous, they exhibit crystal phase heterogeneity with the co-existing domains of the 1T' and 2H crystal phases, and with evidence of MoSe2 in the metastable 1T' phase. We show at single atom level of resolution, that tungsten and molybdenum can be found in both the 1T' and 2H lattices. The formation of heterophase 1T'/2H WxMo1-xSe2 electrocatalysts allowed for a considerable improvement in the activity for the acidic hydrogen evolution reaction (HER) compared to pristine, 1T'-dominated, WSe2. This work can pave the way towards engineered functional nanomaterials where properties, such as electronic and catalytic, have to be controlled at the atomic scale.
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Affiliation(s)
| | - Gang Cheng
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Mauro Och
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Pawel Palczynski
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
| | - Khalil El Hajraoui
- SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Daresbury WA4 4AD, UK
- York NanoCentre & Department of Physics, University of York, York YO10 5DD, UK
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury, Keckwick Lane, Daresbury WA4 4AD, UK
- School of Physics and Astronomy & School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - Cecilia Mattevi
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
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Hennessy M, O'Connell EN, Auge M, Moynihan E, Hofsäss H, Bangert U. Quantification of Ion-Implanted Single-Atom Dopants in Monolayer MoS 2 via HAADF STEM Using the TEMUL Toolkit. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-10. [PMID: 35722923 DOI: 10.1017/s1431927622000757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In recent years, atomic resolution imaging of two-dimensional (2D) materials using scanning transmission electron microscopy (STEM) has become routine. Individual dopant atoms in 2D materials can be located and identified using their contrast in annular dark-field (ADF) STEM. However, in order to understand the effect of these dopant atoms on the host material, there is now the need to locate and quantify them on a larger scale. In this work, we analyze STEM images of MoS2 monolayers that have been ion-implanted with chromium at ultra-low energies. We use functions from the open-source TEMUL Toolkit to create and refine an atomic model of an experimental image based on the positions and intensities of the atomic columns in the image. We then use the refined model to determine the likely composition of each atomic site. Surface contamination stemming from the sample preparation of 2D materials can prevent accurate quantitative identification of individual atoms. We disregard atomic sites from regions of the image with hydrocarbon surface contamination to demonstrate that images acquired using contaminated samples can give significant atom statistics from their clean regions, and can be used to calculate the retention rate of the implanted ions within the host lattice. We find that some of the implanted chromium ions have been successfully integrated into the MoS2 lattice, with 4.1% of molybdenum atoms in the transition metal sublattice replaced with chromium.
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Affiliation(s)
- Michael Hennessy
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Eoghan N O'Connell
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Manuel Auge
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Eoin Moynihan
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
| | - Hans Hofsäss
- II. Institute of Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Ursel Bangert
- Department of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick, Ireland
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Moore K, O’Connell EN, Griffin SM, Downing C, Colfer L, Schmidt M, Nicolosi V, Bangert U, Keeney L, Conroy M. Charged Domain Wall and Polar Vortex Topologies in a Room-Temperature Magnetoelectric Multiferroic Thin Film. ACS APPLIED MATERIALS & INTERFACES 2022; 14:5525-5536. [PMID: 35044754 PMCID: PMC8815039 DOI: 10.1021/acsami.1c17383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Multiferroic topologies are an emerging solution for future low-power magnetic nanoelectronics due to their combined tuneable functionality and mobility. Here, we show that in addition to being magnetoelectric multiferroic at room temperature, thin-film Aurivillius phase Bi6TixFeyMnzO18 is an ideal material platform for both domain wall and vortex topology-based nanoelectronic devices. Utilizing atomic-resolution electron microscopy, we reveal the presence and structure of 180°-type charged head-to-head and tail-to-tail domain walls passing throughout the thin film. Theoretical calculations confirm the subunit cell cation site preference and charged domain wall energetics for Bi6TixFeyMnzO18. Finally, we show that polar vortex-type topologies also form at out-of-phase boundaries of stacking faults when internal strain and electrostatic energy gradients are altered. This study could pave the way for controlled polar vortex topology formation via strain engineering in other multiferroic thin films. Moreover, these results confirm that the subunit cell topological features play an important role in controlling the charge and spin state of Aurivillius phase films and other multiferroic heterostructures.
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Affiliation(s)
- Kalani Moore
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Eoghan N. O’Connell
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Sinéad M. Griffin
- Materials
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Molecular
Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Clive Downing
- Advanced
Microscopy Laboratory & AMBER, Trinity
College Dublin, Dublin D02 PN40, Ireland
| | - Louise Colfer
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Michael Schmidt
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Valeria Nicolosi
- Advanced
Microscopy Laboratory & AMBER, Trinity
College Dublin, Dublin D02 PN40, Ireland
- School of
Chemistry, Trinity College Dublin, Dublin D02 PN40, Ireland
| | - Ursel Bangert
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
| | - Lynette Keeney
- Tyndall
National Institute, University College Cork, Cork T12 R5CP, Ireland
| | - Michele Conroy
- Department
of Physics, Bernal Institute, School of Natural Sciences, University of Limerick, Limerick V94 T9PX, Ireland
- Department
of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, U.K.
- London
Centre for Nanotechnology, Imperial College
London, Exhibition Road, London SW7 2AZ, U.K.
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