1
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Szpytma M, Ślęzak M, Janus W, Nayyef H, Ślęzak T, Mandziak A, Zając M, Wilgocka-Ślęzak D, Menteş TO, Jugovac M, Locatelli A, Kozioł-Rachwał A. Transfer of magnetic anisotropy in epitaxial Co/NiO/Fe trilayers. Sci Rep 2024; 14:1680. [PMID: 38243038 PMCID: PMC10798992 DOI: 10.1038/s41598-024-51896-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 01/10/2024] [Indexed: 01/21/2024] Open
Abstract
The magnetic properties of Co(10 Å)/NiO(40 Å)/Fe trilayer epitaxially grown on W(110) substrate were investigated with use of x-ray magnetic linear dichroism (XMLD) and x-ray magnetic circular dichroism (XMCD). We showed that magnetic anisotropy of Fe film that can be controlled by a thickness-driven spin reorientation transition is transferred via interfacial exchange coupling not only to NiO layer but further to ferromagnetic Co overlayer as well. Similarly, a temperature driven spin reorientation of Fe sublayer induces a reorientation of NiO spin orientation and simultaneous switching of the Co magnetization direction. Finally, by element specific XMCD and XMLD magnetic hysteresis loop measurements we proved that external magnetic field driven reorientation of Fe and Co magnetizations as well as NiO Néel vector are strictly correlated and magnetic anisotropy fields of Fe and Co sublayers are identical despite the different crystal structures.
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Affiliation(s)
- M Szpytma
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland.
| | - M Ślęzak
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - W Janus
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - H Nayyef
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - T Ślęzak
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
| | - A Mandziak
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Krakow, Poland
| | - M Zając
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Krakow, Poland
| | - D Wilgocka-Ślęzak
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Krakow, Poland
| | - T O Menteş
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - M Jugovac
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - A Kozioł-Rachwał
- Faculty of Physics and Applied Computer Science, AGH University of Krakow, Krakow, Poland
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2
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Winchester AJ, Anderson TJ, Hite JK, Elmquist RE, Pookpanratana S. Methodology and implementation of a tunable deep-ultraviolet laser source for photoemission electron microscopy. Ultramicroscopy 2023; 253:113819. [PMID: 37549583 DOI: 10.1016/j.ultramic.2023.113819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/21/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Photoemission electron microscopy (PEEM) is a unique and powerful tool for studying the electronic properties of materials and surfaces. However, it requires intense and well-controlled light sources with photon energies ranging from the UV to soft X-rays for achieving high spatial resolution and image contrast. Traditionally, many PEEMs were installed at synchrotron light sources to access intense and tunable soft X-rays. More recently, the maturation of solid-state lasers has opened a new avenue for laboratory-based PEEMs using laser-based UV light at lower photon energies. Here, we report on the characteristics of a laser-based UV light source that was recently integrated with a PEEM instrument. The system consists of a high repetition rate, tunable wavelength laser coupled to a harmonics generation module, which generates deep-UV radiation from 192 nm to 210 nm. We comment on the spectral characteristics and overall laser system stability, as well as on the effects of space charge within the PEEM microscope at high UV laser fluxes. Further, we show an example of imaging on gallium nitride, where the higher UV photon energy and flux of the laser provides considerably improved image quality, compared to a conventional light source. These results demonstrate the capabilities of laser-based UV light sources for advancing laboratory-based PEEMs.
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Affiliation(s)
- Andrew J Winchester
- Nanoscale Device and Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Travis J Anderson
- Electronics Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC, United States
| | - Jennifer K Hite
- Electronics Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC, United States
| | - Randolph E Elmquist
- Quantum Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Sujitra Pookpanratana
- Nanoscale Device and Characterization Division, National Institute of Standards and Technology, Gaithersburg, MD, United States.
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3
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Grinter D, Shaw BJA, Pang CL, Yim CM, Muryn CA, Hall CA, Maccherozzi F, Dhesi SS, Suzuki M, Yasue T, Koshikawa T, Thornton G. Fabrication of Isolated Iron Nanowires. J Phys Chem Lett 2023; 14:8507-8512. [PMID: 37722000 PMCID: PMC10544030 DOI: 10.1021/acs.jpclett.3c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 09/14/2023] [Indexed: 09/20/2023]
Abstract
Nanoscale interconnects are an important component of molecular electronics. Here we use X-ray spectromicroscopy techniques as well as scanning probe methods to explore the self-assembled growth of insulated iron nanowires as a potential means of supplying an earth abundant solution. The intrinsic anisotropy of a TiO2(110) substrate directs the growth of micron length iron wires at elevated temperatures, with a strong metal-support interaction giving rise to ilmenite (FeTiO3) encapsulation. Iron nanoparticles that decorate the nanowires display magnetic properties that suggest other possible applications.
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Affiliation(s)
- David
C. Grinter
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Bobbie-Jean A. Shaw
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | - Chi L. Pang
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | - Chi-Ming Yim
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
| | | | - Charlotte A. Hall
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
- Department
of Chemistry, University of Reading, Reading, RG6 6AD, U.K.
| | - Francesco Maccherozzi
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Sarnjeet S. Dhesi
- Diamond
Light Source Ltd, Diamond House,
Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K.
| | - Masahiko Suzuki
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Tsuneo Yasue
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Takanori Koshikawa
- Fundamental
Electronics Research Institute, Osaka Electro-Communication
University, Neyagawa-shi, Osaka 572-8530, Japan
| | - Geoff Thornton
- Department
of Chemistry and London Centre for Nanotechnology, University College London, London, WC1H 0AJ, U.K.
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4
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Guo H, Jiménez-Sánchez MD, Michel EG, Martínez-Galera AJ, Gómez-Rodríguez JM. Aperiodic Modulation of Graphene Driven by Oxygen-Induced Reconstruction of Rh(110). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:17930-17938. [PMID: 37744964 PMCID: PMC10513088 DOI: 10.1021/acs.jpcc.3c02643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/04/2023] [Indexed: 09/26/2023]
Abstract
Artificial nanostructuring of graphene has served as a platform to induce variations in its structural and electronic properties, fostering the experimental observation of a wide and fascinating phenomenology. Here, we present an approach to graphene tuning, based on Rh(110) surface reconstruction induced by oxygen atoms intercalation. The resulting nanostructured graphene has been characterized by scanning tunneling microscopy (STM) complemented by low-energy electron microscopy (LEEM), micro low-energy electron diffraction (μ-LEED), micro angle-resolved photoemission spectroscopy (μ-ARPES), and micro X-ray photoelectron spectroscopy (μ-XPS) measurements under ultrahigh vacuum (UHV) conditions at room temperature (RT). It is found that by fine-tuning the O2 exposure amount, a mixture of missing row surface reconstructions of the metal surface below the graphene layer can be induced. This atomic rearrangement under the graphene layer results in aperiodic patterning of the two-dimensional (2D) material. The electronic structure of the resulting nanostructured graphene is dominated by a linear dispersion of the Dirac quasiparticles, characteristic of its free-standing state but with a p-doping character. The local effects of the underlying missing rows on the interfacial chemistry and on the quasiparticle scattering processes in graphene are studied using atomically resolved STM images. The possibilities offered by this nanostructuring approach, which consists in inducing surface reconstructions under graphene, could provide a novel tuning strategy for this 2D material.
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Affiliation(s)
- Haojie Guo
- Departamento
de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | | | - Enrique G. Michel
- Departamento
de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Instituto
Nicolás Cabrera, Universidad Autónoma
de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
| | - Antonio J. Martínez-Galera
- Instituto
Nicolás Cabrera, Universidad Autónoma
de Madrid, E-28049 Madrid, Spain
- Departamento
de Física de Materiales, Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
| | - José M. Gómez-Rodríguez
- Departamento
de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Instituto
Nicolás Cabrera, Universidad Autónoma
de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
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5
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Günther S, Kratky T, Kraus J, Leidinger P, Zeller P, Sala A, Genuzio F, Jugovac M, Menteş TO, Locatelli A. Versatile procedure for the correction of non-isochromatism in XPEEM spectroscopic imaging. Ultramicroscopy 2023; 250:113756. [PMID: 37182363 DOI: 10.1016/j.ultramic.2023.113756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/16/2023] [Accepted: 05/08/2023] [Indexed: 05/16/2023]
Abstract
Non-isochromatism in X-ray PhotoEmission Electron Microscopy (XPEEM) may result in unwanted artifacts especially when working with large field of views. The lack of isochromatism of XPEEM images may result from multiple factors, for instance the energy dispersion of the X-rays on the sample or the effect of one or more dispersive elements in the electron optics of the microscope, or the combination of both. In practice, the photon energy or the electron kinetic energy may vary across the image, complicating image interpretation and analysis. The effect becomes severe when imaging at low magnification upon irradiation with high energy photons. Such imaging demands for a large X-ray illuminating spot size usually achieved by opening the exit slit of the X-ray monochromator while reducing the monochromaticity of the irradiating light. However, we show that the effect is linear and can be fully removed. A versatile correction procedure is presented which leads to true monochromatic photoelectron images at improved signal-to-noise ratio. XPEEM data recorded at the nanospectroscopy beamline of the Elettra synchrotron radiation facility illustrate the working principle of the procedure. Also, reciprocal space XPEEM data such as angle-resolved photoelectron spectroscopy (ARPES) momentum plots suffer from linear energy dispersion artifacts which can be corrected in a similar way. Representative data acquired from graphene synthesized on copper by chemical vapor deposition prove the benefits of the correction procedure.
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Affiliation(s)
- Sebastian Günther
- Chemistry Department, Physical Chemistry with Focus on Catalysis, Technical University of Munich (TUM), Lichtenbergstr 4, Garching D-85748, Germany.
| | - Tim Kratky
- Chemistry Department, Physical Chemistry with Focus on Catalysis, Technical University of Munich (TUM), Lichtenbergstr 4, Garching D-85748, Germany
| | - Jürgen Kraus
- Chemistry Department, Physical Chemistry with Focus on Catalysis, Technical University of Munich (TUM), Lichtenbergstr 4, Garching D-85748, Germany
| | - Paul Leidinger
- Chemistry Department, Physical Chemistry with Focus on Catalysis, Technical University of Munich (TUM), Lichtenbergstr 4, Garching D-85748, Germany
| | - Patrick Zeller
- Chemistry Department, Physical Chemistry with Focus on Catalysis, Technical University of Munich (TUM), Lichtenbergstr 4, Garching D-85748, Germany
| | - Alessandro Sala
- Elettra-Sincrotrone Trieste S.C.P.A., S.S. 14 - km 163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Francesca Genuzio
- Elettra-Sincrotrone Trieste S.C.P.A., S.S. 14 - km 163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Matteo Jugovac
- Elettra-Sincrotrone Trieste S.C.P.A., S.S. 14 - km 163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste S.C.P.A., S.S. 14 - km 163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste S.C.P.A., S.S. 14 - km 163,5 in Area Science Park, Basovizza, Trieste 34149, Italy
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6
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Janus W, Ślęzak T, Ślęzak M, Szpytma M, Dróżdż P, Nayyef H, Mandziak A, Wilgocka-Ślęzak D, Zając M, Jugovac M, Menteş TO, Locatelli A, Kozioł-Rachwał A. Tunable magnetic anisotropy of antiferromagnetic NiO in (Fe)/NiO/MgO/Cr/MgO(001) epitaxial multilayers. Sci Rep 2023; 13:4824. [PMID: 36964276 PMCID: PMC10039026 DOI: 10.1038/s41598-023-31930-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/20/2023] [Indexed: 03/26/2023] Open
Abstract
We report on the magnetic properties of antiferromagnetic NiO(001) thin films in epitaxially grown NiO/MgO(dMgO)/Cr/MgO(001) system for different thicknesses of MgO, dMgO. Results of X-ray Magnetic Linear Dichroism show that together with an increase of dMgO, rotation of NiO spins from in-plane towards out-of-plane direction occurs. Furthermore, we investigated how the proximity of Fe modifies the magnetic state of NiO in Fe/NiO/MgO(dMgO)/Cr/MgO(001). We proved the existence of a multidomain state in NiO as a result of competition between the ferromagnet/antiferromagnet exchange coupling and strain exerted on the NiO by the MgO buffer layer.
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Affiliation(s)
- W Janus
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland.
| | - T Ślęzak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
| | - M Ślęzak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
| | - M Szpytma
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
| | - P Dróżdż
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
| | - H Nayyef
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
| | - A Mandziak
- SOLARIS National Synchrotron Radiation Centre, Jagiellonian University, Krakow, Poland
| | - D Wilgocka-Ślęzak
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Krakow, Poland
| | - M Zając
- SOLARIS National Synchrotron Radiation Centre, Jagiellonian University, Krakow, Poland
| | - M Jugovac
- Elettra-Sincrotrone Trieste S.C.P.A., Basovizza, Trieste, Italy
| | - T O Menteş
- Elettra-Sincrotrone Trieste S.C.P.A., Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra-Sincrotrone Trieste S.C.P.A., Basovizza, Trieste, Italy
| | - A Kozioł-Rachwał
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
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7
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Sala A, Caporali M, Serrano-Ruiz M, Armillotta F, Vesselli E, Genuzio F, Menteş TO, Locatelli A, Comelli G, Africh C, Verdini A. Black or red phosphorus yields the same blue phosphorus film. NANOSCALE 2022; 14:16256-16261. [PMID: 36285832 DOI: 10.1039/d2nr02657k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
After the discovery of graphene, many other 2D materials have been predicted theoretically and successfully prepared. In this context, single-sheet black phosphorus - phosphorene - is emerging as a viable contender in the field of (2D) semiconductors. Phosphorene offers high carrier mobility and an anisotropic structure that gives rise to a modulation of physical and chemical properties. This opens the way to many novel and fascinating applications related to field-effect transistors and optoelectronic devices. In previous studies, a single layer of blue phosphorene intermixed with Au atoms was grown using purified black phosphorus as a precursor. Starting from the observation that phosphorus vapor mainly consists of P clusters, in this work we aimed at obtaining blue phosphorus using much less expensive purified red phosphorus as an evaporant. By means of microscopy, spectroscopy and diffraction experiments, we show that black or red phosphorus deposition on Au(111) substrates yields the same blue phosphorus film.
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Affiliation(s)
- Alessandro Sala
- CNR-IOM Materials Foundry, S. S. 14 km 163.5, Trieste, I-34149, Italy.
- Physics Department, University of Trieste, via Valerio 2, Trieste, I-34127, Italy
| | - Maria Caporali
- CNR-ICCOM Institute of Chemistry of Organometallic Compounds, Via Madonna del Piano 10, Sesto Fiorentino, I-50019, Italy
| | - Manuel Serrano-Ruiz
- CNR-ICCOM Institute of Chemistry of Organometallic Compounds, Via Madonna del Piano 10, Sesto Fiorentino, I-50019, Italy
| | - Francesco Armillotta
- Physics Department, University of Trieste, via Valerio 2, Trieste, I-34127, Italy
| | - Erik Vesselli
- CNR-IOM Materials Foundry, S. S. 14 km 163.5, Trieste, I-34149, Italy.
- Physics Department, University of Trieste, via Valerio 2, Trieste, I-34127, Italy
| | - Francesca Genuzio
- Elettra-Sincrotrone Trieste S.C.p.A, S.S. 14 km 163.5 in AREA Science Park, Trieste, I-34149, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste S.C.p.A, S.S. 14 km 163.5 in AREA Science Park, Trieste, I-34149, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A, S.S. 14 km 163.5 in AREA Science Park, Trieste, I-34149, Italy
| | - Giovanni Comelli
- CNR-IOM Materials Foundry, S. S. 14 km 163.5, Trieste, I-34149, Italy.
- Physics Department, University of Trieste, via Valerio 2, Trieste, I-34127, Italy
| | - Cristina Africh
- CNR-IOM Materials Foundry, S. S. 14 km 163.5, Trieste, I-34149, Italy.
| | - Alberto Verdini
- CNR-IOM Materials Foundry, c/o Physics and Geology Department, University of Perugia, via A. Pascoli 2, Perugia, I-06123, Italy.
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8
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Hamer M, Giampietri A, Kandyba V, Genuzio F, Menteş TO, Locatelli A, Gorbachev RV, Barinov A, Mucha-Kruczyński M. Moiré Superlattice Effects and Band Structure Evolution in Near-30-Degree Twisted Bilayer Graphene. ACS NANO 2022; 16:1954-1962. [PMID: 35073479 PMCID: PMC9007532 DOI: 10.1021/acsnano.1c06439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 01/20/2022] [Indexed: 06/01/2023]
Abstract
In stacks of two-dimensional crystals, mismatch of their lattice constants and misalignment of crystallographic axes lead to formation of moiré patterns. We show that moiré superlattice effects persist in twisted bilayer graphene (tBLG) with large twists and short moiré periods. Using angle-resolved photoemission, we observe dramatic changes in valence band topology across large regions of the Brillouin zone, including the vicinity of the saddle point at M and across 3 eV from the Dirac points. In this energy range, we resolve several moiré minibands and detect signatures of secondary Dirac points in the reconstructed dispersions. For twists θ > 21.8°, the low-energy minigaps are not due to cone anticrossing as is the case at smaller twist angles but rather due to moiré scattering of electrons in one graphene layer on the potential of the other which generates intervalley coupling. Our work demonstrates the robustness of the mechanisms which enable engineering of electronic dispersions of stacks of two-dimensional crystals by tuning the interface twist angles. It also shows that large-angle tBLG hosts electronic minigaps and van Hove singularities of different origin which, given recent progress in extreme doping of graphene, could be explored experimentally.
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Affiliation(s)
- Matthew
J. Hamer
- Department
of Physics, University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
| | | | | | | | | | | | - Roman V. Gorbachev
- Department
of Physics, University of Manchester, Oxford Road, Manchester M13 9PL, United
Kingdom
- National
Graphene Institute, University of Manchester, Booth Street East, Manchester M13 9PL, United Kingdom
- Henry
Royce Institute, Oxford
Road, Manchester M13 9PL, United Kingdom
| | | | - Marcin Mucha-Kruczyński
- Department
of Physics, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
- Centre
for Nanoscience and Nanotechnology, University
of Bath, Claverton Down, Bath BA2
7AY, United Kingdom
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9
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Prince KC, Diviacco B. On "Coherent control in the extreme ultraviolet and attosecond regime by synchrotron radiation" by Hikosaka et al, Nat. Comm. 10, 4988 (2019). Nat Commun 2021; 12:3784. [PMID: 34145233 PMCID: PMC8213757 DOI: 10.1038/s41467-021-24024-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 06/01/2021] [Indexed: 01/16/2023] Open
Affiliation(s)
- Kevin C Prince
- Elettra - Sincrotrone Trieste S.C.p.A, Basovizza, Trieste, Italy. .,Centre for Translational Atomaterials, Swinburne University of Technology, Melbourne, VIC, Australia.
| | - Bruno Diviacco
- Elettra - Sincrotrone Trieste S.C.p.A, Basovizza, Trieste, Italy
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10
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Genuzio F, Giela T, Lucian M, Menteş TO, Brondin CA, Cautero G, Mazalski P, Bonetti S, Korecki J, Locatelli A. A UHV MOKE magnetometer complementing XMCD-PEEM at the Elettra Synchrotron. JOURNAL OF SYNCHROTRON RADIATION 2021; 28:995-1005. [PMID: 33950008 PMCID: PMC8127370 DOI: 10.1107/s1600577521002885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
We report on a custom-built UHV-compatible Magneto-Optical Kerr Effect (MOKE) magnetometer for applications in surface and materials sciences, operating in tandem with the PhotoEmission Electron Microscope (PEEM) endstation at the Nanospectroscopy beamline of the Elettra synchrotron. The magnetometer features a liquid-nitrogen-cooled electromagnet that is fully compatible with UHV operation and produces magnetic fields up to about 140 mT at the sample. Longitudinal and polar MOKE measurement geometries are realized. The magneto-optical detection is based on polarization analysis using a photoelastic modulator. The sample manipulation system is fully compatible with that of the PEEM, making it possible to exchange samples with the beamline endstation, where complementary X-ray imaging and spectroscopy techniques are available. The magnetometer performance is illustrated by experiments on cobalt ultra-thin films, demonstrating close to monolayer sensitivity. The advantages of combining in situ growth, X-ray Magnetic Circular Dichroism imaging (XMCD-PEEM) and MOKE magnetometry into a versatile multitechnique facility are highlighted.
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Affiliation(s)
| | - Tomasz Giela
- CERIC-ERIC, Basovizza, Trieste, Italy
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Kraków, Poland
| | - Matteo Lucian
- Elettra–Sincrotrone Trieste SCpA, Basovizza, Trieste, Italy
| | | | - Carlo Alberto Brondin
- Department of Molecular Sciences and Nanosytems, Ca’ Foscari University of Venice, Venezia, Italy
| | | | - Piotr Mazalski
- Faculty of Physics, University of Białystok, Białystok, Poland
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Poland
| | - Stefano Bonetti
- Department of Molecular Sciences and Nanosytems, Ca’ Foscari University of Venice, Venezia, Italy
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Jozef Korecki
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Poland
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11
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Fortin-Deschênes M, Zschiesche H, Menteş TO, Locatelli A, Jacobberger RM, Genuzio F, Lagos MJ, Biswas D, Jozwiak C, Miwa JA, Ulstrup S, Bostwick A, Rotenberg E, Arnold MS, Botton GA, Moutanabbir O. Pnictogens Allotropy and Phase Transformation during van der Waals Growth. NANO LETTERS 2020; 20:8258-8266. [PMID: 33026227 DOI: 10.1021/acs.nanolett.0c03372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
With their ns2 np3 valence electronic configuration, pnictogens are the only system to crystallize in layered van der Waals (vdW) and quasi-vdW structures throughout the group. Light pnictogens crystallize in the A17 phase, and bulk heavier elements prefer the A7 phase. Herein, we demonstrate that the A17 of heavy pnictogens can be stabilized in antimonene grown on weakly interacting surfaces and that it undergoes a spontaneous thickness-driven transformation to the stable A7 phase. At a critical thickness of ∼4 nm, A17 antimony transforms from AB- to AA-stacked α-antimonene by a diffusionless shuffle transition followed by a gradual relaxation to the A7 phase. Furthermore, the competition between A7- and A17-like bonding affects the electronic structure of the intermediate phase. These results highlight the critical role of the atomic structure and substrate-layer interactions in shaping the stability and properties of layered materials, thus enabling a new degree of freedom to engineer their performance.
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Affiliation(s)
- Matthieu Fortin-Deschênes
- Department of Engineering Physics, École Polytechnique de Montréal, C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - Hannes Zschiesche
- Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Tevfik O Menteş
- Elettra Sincrotrone Trieste S.C.p.A, S.S. 14-km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - Andrea Locatelli
- Elettra Sincrotrone Trieste S.C.p.A, S.S. 14-km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - Robert M Jacobberger
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Francesca Genuzio
- Elettra Sincrotrone Trieste S.C.p.A, S.S. 14-km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - Maureen J Lagos
- Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Deepnarayan Biswas
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Chris Jozwiak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Søren Ulstrup
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Aaron Bostwick
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michael S Arnold
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Gianluigi A Botton
- Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada
| | - Oussama Moutanabbir
- Department of Engineering Physics, École Polytechnique de Montréal, C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada
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12
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von Boehn B, Imbihl R. Dynamics of Ultrathin Vanadium Oxide Layers on Rh(111) and Rh(110) Surfaces During Catalytic Reactions. Front Chem 2020; 8:707. [PMID: 32974277 PMCID: PMC7472780 DOI: 10.3389/fchem.2020.00707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/09/2020] [Indexed: 11/13/2022] Open
Abstract
Over the past 35 years rate oscillations and chemical wave patterns have been extensively studied on metal surfaces, while little is known about the dynamics of catalytic oxide surfaces under reaction conditions. Here we report on the behavior of ultrathin V oxide layers epitaxially grown on Rh(111) and Rh(110) single crystal surfaces during catalytic methanol oxidation. We use photoemission electron microscopy and low-energy electron microscopy to study the surface dynamics in the 10-6 to 10-2 mbar range. On VO x /Rh(111) we find a ripening mechanism in which VO x islands of macroscopic size move toward each other and coalesce under reaction conditions. A polymerization/depolymerization mechanism of VO x that is sensitive to gradients in the oxygen coverage explains this behavior. The existence of a substructure in VO x islands gives rise to an instability, in which a VO x island shrinks and expands around a critical radius in an oscillatory manner. At 10-2 mbar the VO x islands are no longer stable but they disintegrate, leading to turbulent redistribution dynamics of VO x . On the more open and thermodynamically less stable Rh(110) surface the behavior of VO x is much more complex than on Rh(111), as V can also populate subsurface sites. At low V coverage, one finds traveling interface pulses in the bistable range. A state-dependent anisotropy of the surface is presumably responsible for intriguing chemical wave patterns: wave fragments traveling along certain crystallographic directions, and coexisting different front geometries in the range of dynamic bistability. Annealing to 1000 K causes the formation of macroscopic VO x islands. Under more reducing conditions dendritic growth of a VO x overlayer is observed.
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Affiliation(s)
- Bernhard von Boehn
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover, Hanover, Germany
| | - Ronald Imbihl
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover, Hanover, Germany
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13
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Slęzak M, Dróżdż P, Janus W, Nayyef H, Kozioł-Rachwał A, Szpytma M, Zając M, Menteş TO, Genuzio F, Locatelli A, Slęzak T. Fine tuning of ferromagnet/antiferromagnet interface magnetic anisotropy for field-free switching of antiferromagnetic spins. NANOSCALE 2020; 12:18091-18095. [PMID: 32856646 DOI: 10.1039/d0nr04193a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We show that in a uniform thickness NiO(111)/Fe(110) epitaxial bilayer system, at given temperature near 300 K, two magnetic states with orthogonal spin orientations can be stabilized in antiferromagnetic NiO. Field-free, reversible switching between these two antiferromagnetic states is demonstrated. The observed phenomena arise from the unique combination of precisely tuned interface magnetic anisotropy, thermal hysteresis of spin reorientation transition and interfacial ferromagnet/antiferromagnet exchange coupling. The possibility of field-free switching between two magnetic states in an antiferromagnet is fundamentally interesting and can lead to new ideas in heat assisted magnetic recording technology.
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Affiliation(s)
- M Slęzak
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - P Dróżdż
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - W Janus
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - H Nayyef
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - A Kozioł-Rachwał
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - M Szpytma
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
| | - M Zając
- National Synchrotron Radiation Centre SOLARIS, Jagiellonian University, Kraków, Poland
| | - T O Menteş
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - F Genuzio
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra - Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - T Slęzak
- AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Kraków, Poland.
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14
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Purbawati A, Coraux J, Vogel J, Hadj-Azzem A, Wu N, Bendiab N, Jegouso D, Renard J, Marty L, Bouchiat V, Sulpice A, Aballe L, Foerster M, Genuzio F, Locatelli A, Menteş TO, Han ZV, Sun X, Núñez-Regueiro M, Rougemaille N. In-Plane Magnetic Domains and Néel-like Domain Walls in Thin Flakes of the Room Temperature CrTe 2 Van der Waals Ferromagnet. ACS APPLIED MATERIALS & INTERFACES 2020; 12:30702-30710. [PMID: 32515190 DOI: 10.1021/acsami.0c07017] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The recent discovery of magnetic van der Waals (vdW) materials triggered a wealth of investigations in materials science and now offers genuinely new prospects for both fundamental and applied research. Although the catalog of vdW ferromagnets is rapidly expanding, most of them have a Curie temperature below 300 K, a notable disadvantage for potential applications. Combining element-selective X-ray magnetic imaging and magnetic force microscopy, we resolve at room temperature the magnetic domains and domain walls in micron-sized flakes of the CrTe2 vdW ferromagnet. Flux-closure magnetic patterns suggesting an in-plane six-fold symmetry are observed. Upon annealing the material above its Curie point (315 K), the magnetic domains disappear. By cooling back the sample, a different magnetic domain distribution is obtained, indicating material stability and lack of magnetic memory upon thermal cycling. The domain walls presumably have Néel texture, are preferentially oriented along directions separated by 120°, and have a width of several tens of nanometers. Besides microscopic mapping of magnetic domains and domain walls, the coercivity of the material is found to be of a few millitesla only, showing that the CrTe2 compound is magnetically soft. The coercivity is found to increase as the volume of the material decreases.
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Affiliation(s)
- Anike Purbawati
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Johann Coraux
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Jan Vogel
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | | | - NianJheng Wu
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Nedjma Bendiab
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - David Jegouso
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Julien Renard
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Laetitia Marty
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Vincent Bouchiat
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - André Sulpice
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
| | - Lucia Aballe
- ALBA Synchrotron Light Facility, 08290 Cerdanyola Del Valles, Spain
| | - Michael Foerster
- ALBA Synchrotron Light Facility, 08290 Cerdanyola Del Valles, Spain
| | - Francesca Genuzio
- Elettra-Sincrotrone Trieste S.C.p.A., S:S. 14, km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A., S:S. 14, km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste S.C.p.A., S:S. 14, km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Zheng Vitto Han
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
- School of Material Science and Engineering, University of Science and Technology of China, Anhui 230026, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, P. R.China
| | - Xingdan Sun
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
- School of Material Science and Engineering, University of Science and Technology of China, Anhui 230026, China
| | | | - Nicolas Rougemaille
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NEEL, 38000 Grenoble, France
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15
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Menteş TO, Genuzio F, Schánilec V, Sadílek J, Rougemaille N, Locatelli A. Coherent x-ray scattering in an XPEEM setup. Ultramicroscopy 2020; 216:113035. [PMID: 32544784 DOI: 10.1016/j.ultramic.2020.113035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/17/2020] [Accepted: 05/24/2020] [Indexed: 11/19/2022]
Abstract
X-ray photoemission electron microscopy, one of the most successful imaging tools at synchrotrons, is known to have limitations related to the application of external fields and to the short electron mean free path. In order to overcome such issues, we adapt an existing XPEEM instrument to simultaneously perform coherent x-ray scattering measurements in reflectivity mode, thus adding a complementary method to XPEEM. Photon-in photon-out x-ray scattering provides the sensitivity to buried interfaces as well as the possibility to work under external fields, which is challenging when using charged particles for imaging. XPEEM, in turn, greatly alleviates the difficulties associated with the reconstruction methods used in coherent diffraction imaging. The combination of the two methods is demonstrated for an artifical spin-ice lattice showing both chemical and magnetic contrast.
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Affiliation(s)
- T O Menteş
- Sincrotrone Trieste S.C.p.A., Basovizza-Trieste 34149, Italy.
| | - F Genuzio
- Sincrotrone Trieste S.C.p.A., Basovizza-Trieste 34149, Italy
| | - V Schánilec
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NÉEL, Grenoble 38000, France; Central European Institute of Technology, CEITEC BUT, Brno University of Technology, Purkyňova 123, Brno 612 00, Czech Republic
| | - J Sadílek
- Central European Institute of Technology, CEITEC BUT, Brno University of Technology, Purkyňova 123, Brno 612 00, Czech Republic
| | - N Rougemaille
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut NÉEL, Grenoble 38000, France
| | - A Locatelli
- Sincrotrone Trieste S.C.p.A., Basovizza-Trieste 34149, Italy
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16
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Kowalczyk PJ, Brown SA, Maerkl T, Lu Q, Chiu CK, Liu Y, Yang SA, Wang X, Zasada I, Genuzio F, Menteş TO, Locatelli A, Chiang TC, Bian G. Realization of Symmetry-Enforced Two-Dimensional Dirac Fermions in Nonsymmorphic α-Bismuthene. ACS NANO 2020; 14:1888-1894. [PMID: 31971774 DOI: 10.1021/acsnano.9b08136] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) Dirac-like electron gases have attracted tremendous research interest ever since the discovery of free-standing graphene. The linear energy dispersion and nontrivial Berry phase play a pivotal role in the electronic, optical, mechanical, and chemical properties of 2D Dirac materials. The known 2D Dirac materials are gapless only within certain approximations, for example, in the absence of spin-orbit coupling (SOC). Here, we report a route to establishing robust Dirac cones in 2D materials with nonsymmorphic crystal lattice. The nonsymmorphic symmetry enforces Dirac-like band dispersions around certain high-symmetry momenta in the presence of SOC. Through μ-ARPES measurements, we observe Dirac-like band dispersions in α-bismuthene. The nonsymmorphic lattice symmetry is confirmed by μ-low-energy electron diffraction and scanning tunneling microscopy. Our first-principles simulations and theoretical topological analysis demonstrate the correspondence between nonsymmorphic symmetry and Dirac states. This mechanism can be straightforwardly generalized to other nonsymmorphic materials. The results enlighten the search of symmetry-enforced Dirac fermions in the vast uncharted world of nonsymmorphic 2D materials.
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Affiliation(s)
- Pawel J Kowalczyk
- Department of Solid State Physics, Faculty of Physics and Applied Informatics , University of Lodz , 90-236 Lodz , Pomorska 149/153, Poland
| | - Simon A Brown
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences , University of Canterbury , Private Bag 4800 , Christchurch 8140 , New Zealand
| | - Tobias Maerkl
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences , University of Canterbury , Private Bag 4800 , Christchurch 8140 , New Zealand
| | - Qiangsheng Lu
- Department of Physics and Astronomy , University of Missouri , Columbia , Missouri 65211 , United States
| | - Ching-Kai Chiu
- Kavli Institute for Theoretical Sciences , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Ying Liu
- Research Laboratory for Quantum Materials , Singapore University of Technology and Design , Singapore 487372
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials , Singapore University of Technology and Design , Singapore 487372
| | - Xiaoxiong Wang
- College of Science , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Ilona Zasada
- Department of Solid State Physics, Faculty of Physics and Applied Informatics , University of Lodz , 90-236 Lodz , Pomorska 149/153, Poland
| | - Francesca Genuzio
- Elettra - Sincrotrone Trieste S.C.p.A. , Basovizza, I-34149 Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra - Sincrotrone Trieste S.C.p.A. , Basovizza, I-34149 Trieste , Italy
| | - Andrea Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A. , Basovizza, I-34149 Trieste , Italy
| | - Tai-Chang Chiang
- Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801-3080 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , 104 South Goodwin Avenue , Urbana , Illinois 61801-2902 , United States
| | - Guang Bian
- Department of Physics and Astronomy , University of Missouri , Columbia , Missouri 65211 , United States
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17
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Hajiri T, Baldrati L, Lebrun R, Filianina M, Ross A, Tanahashi N, Kuroda M, Gan WL, Menteş TO, Genuzio F, Locatelli A, Asano H, Kläui M. Spin structure and spin Hall magnetoresistance of epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:445804. [PMID: 31392970 DOI: 10.1088/1361-648x/ab303c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report a combined study of imaging the antiferromagnetic (AFM) spin structure and measuring the spin Hall magnetoresistance (SMR) in epitaxial thin films of the insulating non-collinear antiferromagnet SmFeO3. X-ray magnetic linear dichroism photoemission electron microscopy measurements reveal that the AFM spins of the SmFeO3(1 1 0) align in the plane of the film. Angularly dependent magnetoresistance measurements show that SmFeO3/Ta bilayers exhibit a positive SMR, in contrast to the negative SMR expected in previously studied collinear AFMs. The SMR amplitude increases linearly with increasing external magnetic field at higher magnetic fields, suggesting that field-induced canting of the AFM spins plays an important role. In contrast, around the coercive field, no detectable SMR signal is observed, indicating that the SMR of the AFM and canting magnetization components cancel out. Below 50 K, the SMR amplitude increases sizably by a factor of two as compared to room temperature, which likely correlates with the long-range ordering of the Sm ions. Our results show that the SMR is a sensitive technique for non-equilibrium spin systems of non-collinear AFMs.
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Affiliation(s)
- T Hajiri
- Department of Materials Physics, Nagoya University, Nagoya 464-8603, Japan
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18
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Aballe L, Foerster M, Cabrejo M, Prat J, Pittana P, Sergo R, Lucian M, Barnaba M, Menteş TO, Locatelli A. Pulse picking in synchrotron-based XPEEM. Ultramicroscopy 2019; 202:10-17. [PMID: 30928638 DOI: 10.1016/j.ultramic.2019.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 03/18/2019] [Indexed: 10/27/2022]
Abstract
We report on a simple and cost-effective device for high-speed gating in photoemission electron microscopy (PEEM) with pulsed photon sources. This device is based on miniaturized electrode plates, which deflect the photoelectron beam inside the imaging column of the microscope so that it is either accepted or blocked in its path towards the detector. The gating device is optimized for installation on the Elmitec SPELEEM III microscope. Due to the compact design, it can be driven by voltage pulses of low amplitude (few volts), delivered by commercially available signal generators. Most notably, our device allows for stroboscopic data collection with on-time of less than 10 ns and at a rate in the range from 1 MHz to 250 MHz, making it suitable for usage in both hybrid and standard multi-bunch operation of the synchrotron ring. We demonstrate applications of pump-probe imaging at high lateral resolution, namely magnetic imaging and PEEM imaging of surface acoustic waves.
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Affiliation(s)
- Lucia Aballe
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain.
| | - Michael Foerster
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Meritxell Cabrejo
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Jordi Prat
- ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Valles, Spain
| | - Paolo Pittana
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Rudi Sergo
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Matteo Lucian
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Maurizio Barnaba
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy.
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19
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Aristov VY, Chaika AN, Molodtsova OV, Babenkov SV, Locatelli A, Menteş TO, Sala A, Potorochin D, Marchenko D, Murphy B, Walls B, Zhussupbekov K, Shvets IV. Layer-by-Layer Graphene Growth on β-SiC/Si(001). ACS NANO 2019; 13:526-535. [PMID: 30525448 DOI: 10.1021/acsnano.8b07237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The mechanism of few-layer graphene growth on the technologically relevant cubic-SiC/Si(001) substrate is uncovered using high-resolution core-level and angle-resolved photoelectron spectroscopy, low-energy electron microscopy, and microspot low-energy electron diffraction. The thickness of the graphitic overlayer supported on the silicon carbide substrate and related changes in the surface structure are precisely controlled by monitoring the progress of the surface graphitization in situ during high-temperature graphene synthesis, using a combination of microspectroscopic techniques. The experimental data reveal gradual changes in the preferential graphene lattice orientations at the initial stages of the few-layer graphene growth on SiC(001) and can act as reference data for controllable growth of single-, double-, and triple-layer graphene on silicon carbide substrates.
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Affiliation(s)
- Victor Yu Aristov
- Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85 , D-22607 Hamburg , Germany
- Institute of Solid State Physics of the Russian Academy of Sciences , 2 Academician Ossipyan Street , Chernogolovka , Moscow District 142432 , Russian Federation
| | - Alexander N Chaika
- Institute of Solid State Physics of the Russian Academy of Sciences , 2 Academician Ossipyan Street , Chernogolovka , Moscow District 142432 , Russian Federation
- CRANN, School of Physics , Trinity College Dublin , Dublin 2 , Ireland
| | - Olga V Molodtsova
- Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85 , D-22607 Hamburg , Germany
- National Research University of Information Technologies, Mechanics and Optics , Kronverksky prospekt 49 , 197101 Saint Petersburg , Russian Federation
| | - Sergey V Babenkov
- Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85 , D-22607 Hamburg , Germany
- Institut für Physik , Johannes Gutenberg-Universität , Staudingerweg 7 , D-55099 Mainz , Germany
| | - Andrea Locatelli
- Elettra Sincrotrone Trieste S.C.p.A. , S.S. 14 km 163.5 in AREA Science Park, I-34149 Basovizza , Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra Sincrotrone Trieste S.C.p.A. , S.S. 14 km 163.5 in AREA Science Park, I-34149 Basovizza , Trieste , Italy
| | - Alessandro Sala
- Elettra Sincrotrone Trieste S.C.p.A. , S.S. 14 km 163.5 in AREA Science Park, I-34149 Basovizza , Trieste , Italy
| | - Dmitrii Potorochin
- Deutsches Elektronen-Synchrotron DESY , Notkestrasse 85 , D-22607 Hamburg , Germany
- National Research University of Information Technologies, Mechanics and Optics , Kronverksky prospekt 49 , 197101 Saint Petersburg , Russian Federation
- Institute of Experimental Physics , TU Bergakademie Freiberg , Leipziger Straße 23 , D-09599 Freiberg , Germany
| | - Dmitry Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie , Albert-Einstein-Straße 15 , D-12489 Berlin , Germany
| | - Barry Murphy
- CRANN, School of Physics , Trinity College Dublin , Dublin 2 , Ireland
| | - Brian Walls
- CRANN, School of Physics , Trinity College Dublin , Dublin 2 , Ireland
| | | | - Igor V Shvets
- CRANN, School of Physics , Trinity College Dublin , Dublin 2 , Ireland
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20
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Baeumer C, Funck C, Locatelli A, Menteş TO, Genuzio F, Heisig T, Hensling F, Raab N, Schneider CM, Menzel S, Waser R, Dittmann R. In-Gap States and Band-Like Transport in Memristive Devices. NANO LETTERS 2019; 19:54-60. [PMID: 30241437 DOI: 10.1021/acs.nanolett.8b03023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Point defects such as oxygen vacancies cause emergent phenomena such as resistive switching in transition-metal oxides, but their influence on the electron-transport properties is far from being understood. Here, we employ direct mapping of the electronic structure of a memristive device by spectromicroscopy. We find that oxygen vacancies result in in-gap states that we use as input for single-band transport simulations. Because the in-gap states are situated below the Fermi level, they do not contribute to the current directly but impact the shape of the conduction band. Accordingly, we can describe our devices with band-like transport and tunneling across the Schottky barrier at the interface.
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Affiliation(s)
- Christoph Baeumer
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Carsten Funck
- Institute for Electronic Materials, IWE2 , RWTH Aachen University , 52074 Aachen , Germany
| | - Andrea Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Francesca Genuzio
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 km - 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Thomas Heisig
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Felix Hensling
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Nicolas Raab
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Claus M Schneider
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Stephan Menzel
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
| | - Rainer Waser
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
- Institute for Electronic Materials, IWE2 , RWTH Aachen University , 52074 Aachen , Germany
| | - Regina Dittmann
- Peter Gruenberg Institute , Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich , Germany
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21
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Genoni P, Genuzio F, Menteş TO, Santos B, Sala A, Lenardi C, Locatelli A. Magnetic Patterning by Electron Beam-Assisted Carbon Lithography. ACS APPLIED MATERIALS & INTERFACES 2018; 10:27178-27187. [PMID: 30019889 DOI: 10.1021/acsami.8b07485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the proof of principle of a scalable method for writing the magnetic state by electron-stimulated molecular dissociative adsorption on ultrathin Co on Re(0001). Intense microfocused low-energy electron beams are used to promote the formation of surface carbides and graphitic carbon through the fragmentation of carbon monoxide. Upon annealing at the CO desorption temperature, carbon persists in the irradiated areas, whereas the clean surface is recovered elsewhere, giving origin to chemical patterns with nanometer-sharp edges. The accumulation of carbon is found to induce an in-plane to out-of-plane spin reorientation transition in Co, manifested by the appearance of striped magnetic domains. Irradiation at doses in excess of 1000 L of CO followed by ultrahigh vacuum annealing at 380 °C determines the formation of a graphitic overlayer in the irradiated areas, under which Co exhibits out-of-plane magnetic anisotropy. Domains with opposite magnetization are separated here by chiral Neél walls. Our fabrication protocol adds lateral control to spin reorientation transitions, permitting to tune the magnetic anisotropy within arbitrary regions of mesoscopic size. We envisage applications in the nano-engineering of graphene-spaced stacks exhibiting the desired magnetic state and properties.
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Affiliation(s)
- Pietro Genoni
- CIMAINA, Department of Physics , Università degli Studi di Milano , via Celoria 16 , I-20133 Milan , Italy
| | - Francesca Genuzio
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Benito Santos
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
| | - Alessandro Sala
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
- Department of Physics , Università degli Studi di Trieste , via Valerio 2 , I-34127 Trieste , Italy
| | - Cristina Lenardi
- CIMAINA, Department of Physics , Università degli Studi di Milano , via Celoria 16 , I-20133 Milan , Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park , Basovizza, I-34149 Trieste , Italy
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22
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Vlaic S, Rougemaille N, Artaud A, Renard V, Huder L, Rouvière JL, Kimouche A, Santos B, Locatelli A, Guisset V, David P, Chapelier C, Magaud L, Canals B, Coraux J. Graphene as a Mechanically Active, Deformable Two-Dimensional Surfactant. J Phys Chem Lett 2018; 9:2523-2531. [PMID: 29688019 DOI: 10.1021/acs.jpclett.8b00586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In crystal growth, surfactants are additive molecules used in dilute amount or as dense, permeable layers to control surface morphologies. We investigate the properties of a strikingly different surfactant: a 2D and covalent layer with close atomic packing, graphene. Using in situ, real-time electron microscopy, scanning tunneling microscopy, kinetic Monte Carlo simulations, and continuum mechanics calculations, we reveal why metallic atomic layers can grow in a 2D manner below an impermeable graphene membrane. Upon metal growth, graphene dynamically opens nanochannels called wrinkles, facilitating mass transport while at the same time storing and releasing elastic energy via lattice distortions. Graphene thus behaves as a mechanically active, deformable surfactant. The wrinkle-driven mass transport of the metallic layer intercalated between graphene and the substrate is observed for two graphene-based systems, characterized by different physicochemical interactions, between graphene and the substrate and between the intercalated material and graphene. The deformable surfactant character of graphene that we unveil should then apply to a broad variety of species, opening new avenues for using graphene as a 2D surfactant forcing the growth of flat films, nanostructures, and unconventional crystalline phases.
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Affiliation(s)
- Sergio Vlaic
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
- LPEM, ESPCI Paris, PSL Research University , CNRS, Sorbonne Universités, UPMC University of Paris 6 , 10 rue Vauquelin , Paris F-75005 , France
| | - Nicolas Rougemaille
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Alexandre Artaud
- Univ. Grenoble Alpes , CEA, INAC, PHELIQS, MEM , 38000 Grenoble , France
| | - Vincent Renard
- Univ. Grenoble Alpes , CEA, INAC, PHELIQS, MEM , 38000 Grenoble , France
| | - Loïc Huder
- Univ. Grenoble Alpes , CEA, INAC, PHELIQS, MEM , 38000 Grenoble , France
| | - Jean-Luc Rouvière
- Univ. Grenoble Alpes , CEA, INAC, PHELIQS, MEM , 38000 Grenoble , France
| | - Amina Kimouche
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Benito Santos
- Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 - km 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A. , Strada Statale 14 - km 163,5 in AREA Science Park , I-34149 Basovizza , Trieste , Italy
| | - Valérie Guisset
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Philippe David
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Claude Chapelier
- Univ. Grenoble Alpes , CEA, INAC, PHELIQS, MEM , 38000 Grenoble , France
| | - Laurence Magaud
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Benjamin Canals
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
| | - Johann Coraux
- Univ. Grenoble Alpes, CNRS, Institut NEEL , Grenoble INP , 38000 Grenoble , France
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23
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Forti S, Rossi A, Büch H, Cavallucci T, Bisio F, Sala A, Menteş TO, Locatelli A, Magnozzi M, Canepa M, Müller K, Link S, Starke U, Tozzini V, Coletti C. Electronic properties of single-layer tungsten disulfide on epitaxial graphene on silicon carbide. NANOSCALE 2017; 9:16412-16419. [PMID: 29058741 DOI: 10.1039/c7nr05495e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This work reports an electronic and micro-structural study of an appealing system for optoelectronics: tungsten disulfide (WS2) on epitaxial graphene (EG) on SiC(0001). The WS2 is grown via chemical vapor deposition (CVD) onto the EG. Low-energy electron diffraction (LEED) measurements assign the zero-degree orientation as the preferential azimuthal alignment for WS2/EG. The valence-band (VB) structure emerging from this alignment is investigated by means of photoelectron spectroscopy measurements, with both high space and energy resolution. We find that the spin-orbit splitting of monolayer WS2 on graphene is of 462 meV, larger than what is reported to date for other substrates. We determine the value of the work function for the WS2/EG to be 4.5 ± 0.1 eV. A large shift of the WS2 VB maximum is observed as well, due to the lowering of the WS2 work function caused by the donor-like interfacial states of EG. Density functional theory (DFT) calculations carried out on a coincidence supercell confirm the experimental band structure to an excellent degree. X-ray photoemission electron microscopy (XPEEM) measurements performed on single WS2 crystals confirm the van der Waals nature of the interface coupling between the two layers. In virtue of its band alignment and large spin-orbit splitting, this system gains strong appeal for optical spin-injection experiments and opto-spintronic applications in general.
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Affiliation(s)
- Stiven Forti
- Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa, Italy.
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24
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Fortin-Deschênes M, Waller O, Menteş TO, Locatelli A, Mukherjee S, Genuzio F, Levesque PL, Hébert A, Martel R, Moutanabbir O. Synthesis of Antimonene on Germanium. NANO LETTERS 2017; 17:4970-4975. [PMID: 28678509 DOI: 10.1021/acs.nanolett.7b02111] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The lack of large-area synthesis processes on substrates compatible with industry requirements has been one of the major hurdles facing the integration of 2D materials in mainstream technologies. This is particularly the case for the recently discovered monoelemental group V 2D materials which can only be produced by exfoliation or growth on exotic substrates. Herein, to overcome this limitation, we demonstrate a scalable method to synthesize antimonene on germanium substrates using solid-source molecular beam epitaxy. This emerging 2D material has been attracting a great deal of attention due to its high environmental stability and its outstanding optical and electronic properties. In situ low energy electron microscopy allowed the real time investigation and optimization of the 2D growth. Theoretical calculations combined with atomic-scale microscopic and spectroscopic measurements demonstrated that the grown antimonene sheets are of high crystalline quality, interact weakly with germanium, exhibit semimetallic characteristics, and remain stable under ambient conditions. This achievement paves the way for the integration of antimonene in innovative nanoscale and quantum technologies compatible with the current semiconductor manufacturing.
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Affiliation(s)
- M Fortin-Deschênes
- Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - O Waller
- Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - T O Menteş
- Elettra-Sincrotrone Trieste S.C.p.A. , S.S. 14 - km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A. , S.S. 14 - km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - S Mukherjee
- Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - F Genuzio
- Elettra-Sincrotrone Trieste S.C.p.A. , S.S. 14 - km 163, 5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - P L Levesque
- Département de Chimie, Université de Montréal , 2900 boulevard Edouard Montpetit, Montréal, Québec H3T 1J4, Canada
| | - A Hébert
- Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - R Martel
- Département de Chimie, Université de Montréal , 2900 boulevard Edouard Montpetit, Montréal, Québec H3T 1J4, Canada
| | - O Moutanabbir
- Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
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25
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Baeumer C, Valenta R, Schmitz C, Locatelli A, Menteş TO, Rogers SP, Sala A, Raab N, Nemsak S, Shim M, Schneider CM, Menzel S, Waser R, Dittmann R. Subfilamentary Networks Cause Cycle-to-Cycle Variability in Memristive Devices. ACS NANO 2017; 11:6921-6929. [PMID: 28661649 DOI: 10.1021/acsnano.7b02113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A major obstacle for the implementation of redox-based memristive memory or logic technology is the large cycle-to-cycle and device-to-device variability. Here, we use spectromicroscopic photoemission threshold analysis and operando XAS analysis to experimentally investigate the microscopic origin of the variability. We find that some devices exhibit variations in the shape of the conductive filament or in the oxygen vacancy distribution at and around the filament. In other cases, even the location of the active filament changes from one cycle to the next. We propose that both effects originate from the coexistence of multiple (sub)filaments and that the active, current-carrying filament may change from cycle to cycle. These findings account for the observed variability in device performance and represent the scientific basis, rather than prior purely empirical engineering approaches, for developing stable memristive devices.
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Affiliation(s)
- Christoph Baeumer
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Richard Valenta
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Christoph Schmitz
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Andrea Locatelli
- Elettra-Sincrotrone, S.C.p.A , S.S 14-km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone, S.C.p.A , S.S 14-km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Steven P Rogers
- Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois , Urbana, Illinois 61801, United States
| | - Alessandro Sala
- Elettra-Sincrotrone, S.C.p.A , S.S 14-km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| | - Nicolas Raab
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Slavomir Nemsak
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Moonsub Shim
- Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois , Urbana, Illinois 61801, United States
| | - Claus M Schneider
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Stephan Menzel
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
| | - Rainer Waser
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
- Institute for Electronic Materials, IWE2, RWTH Aachen University , 52074 Aachen, Germany
| | - Regina Dittmann
- Peter Gruenberg Institute, Forschungszentrum Juelich GmbH and JARA-FIT , 52425 Juelich, Germany
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26
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Man MKL, Margiolakis A, Deckoff-Jones S, Harada T, Wong EL, Krishna MBM, Madéo J, Winchester A, Lei S, Vajtai R, Ajayan PM, Dani KM. Imaging the motion of electrons across semiconductor heterojunctions. NATURE NANOTECHNOLOGY 2017; 12:36-40. [PMID: 27723731 DOI: 10.1038/nnano.2016.183] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/22/2016] [Indexed: 05/22/2023]
Abstract
Technological progress since the late twentieth century has centred on semiconductor devices, such as transistors, diodes and solar cells. At the heart of these devices is the internal motion of electrons through semiconductor materials due to applied electric fields or by the excitation of photocarriers. Imaging the motion of these electrons would provide unprecedented insight into this important phenomenon, but requires high spatial and temporal resolution. Current studies of electron dynamics in semiconductors are generally limited by the spatial resolution of optical probes, or by the temporal resolution of electronic probes. Here, by combining femtosecond pump-probe techniques with spectroscopic photoemission electron microscopy, we imaged the motion of photoexcited electrons from high-energy to low-energy states in a type-II 2D InSe/GaAs heterostructure. At the instant of photoexcitation, energy-resolved photoelectron images revealed a highly non-equilibrium distribution of photocarriers in space and energy. Thereafter, in response to the out-of-equilibrium photocarriers, we observed the spatial redistribution of charges, thus forming internal electric fields, bending the semiconductor bands, and finally impeding further charge transfer. By assembling images taken at different time-delays, we produced a movie lasting a few trillionths of a second of the electron-transfer process in the photoexcited type-II heterostructure-a fundamental phenomenon in semiconductor devices such as solar cells. Quantitative analysis and theoretical modelling of spatial variations in the movie provide insight into future solar cells, 2D materials and other semiconductor devices.
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Affiliation(s)
- Michael K L Man
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Athanasios Margiolakis
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Skylar Deckoff-Jones
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Takaaki Harada
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - E Laine Wong
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - M Bala Murali Krishna
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Julien Madéo
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Andrew Winchester
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
| | - Sidong Lei
- Department of Materials Science and Nanoengineering, Rice University, Texas 77005, USA
| | - Robert Vajtai
- Department of Materials Science and Nanoengineering, Rice University, Texas 77005, USA
| | - Pulickel M Ajayan
- Department of Materials Science and Nanoengineering, Rice University, Texas 77005, USA
| | - Keshav M Dani
- Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-495, Japan
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27
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Boulle O, Vogel J, Yang H, Pizzini S, de Souza Chaves D, Locatelli A, Menteş TO, Sala A, Buda-Prejbeanu LD, Klein O, Belmeguenai M, Roussigné Y, Stashkevich A, Chérif SM, Aballe L, Foerster M, Chshiev M, Auffret S, Miron IM, Gaudin G. Room-temperature chiral magnetic skyrmions in ultrathin magnetic nanostructures. NATURE NANOTECHNOLOGY 2016; 11:449-454. [PMID: 26809057 DOI: 10.1038/nnano.2015.315] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/01/2015] [Indexed: 06/05/2023]
Abstract
Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometre size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetization at the nanoscale. Chiral skyrmion structures have so far been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films, and under an external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral Néel internal structure, which we explain as due to the large strength of the Dzyaloshinskii-Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions.
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Affiliation(s)
- Olivier Boulle
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Jan Vogel
- CNRS, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
- Univ. Grenoble Alpes, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
| | - Hongxin Yang
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Stefania Pizzini
- CNRS, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
- Univ. Grenoble Alpes, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
| | - Dayane de Souza Chaves
- CNRS, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
- Univ. Grenoble Alpes, Institut Néel, 25 avenue des Martyrs, B.P. 166, Grenoble Cedex 9 38042, France
| | - Andrea Locatelli
- Elettra-Sincrotrone, S.C.p.A, S.S 14 - km 163.5 in AREA Science Park 34149 Basovizza, Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone, S.C.p.A, S.S 14 - km 163.5 in AREA Science Park 34149 Basovizza, Trieste, Italy
| | - Alessandro Sala
- Elettra-Sincrotrone, S.C.p.A, S.S 14 - km 163.5 in AREA Science Park 34149 Basovizza, Trieste, Italy
| | - Liliana D Buda-Prejbeanu
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Olivier Klein
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Mohamed Belmeguenai
- LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, Villetaneuse 93430, France
| | - Yves Roussigné
- LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, Villetaneuse 93430, France
| | - Andrey Stashkevich
- LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, Villetaneuse 93430, France
| | - Salim Mourad Chérif
- LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 avenue Jean-Baptiste Clément, Villetaneuse 93430, France
| | - Lucia Aballe
- ALBA Synchrotron Light Facility, Carretera BP 1413, Km. 3.3, Cerdanyola del Vallès, Barcelona 08290, Spain
| | - Michael Foerster
- ALBA Synchrotron Light Facility, Carretera BP 1413, Km. 3.3, Cerdanyola del Vallès, Barcelona 08290, Spain
| | - Mairbek Chshiev
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Stéphane Auffret
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Ioan Mihai Miron
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
| | - Gilles Gaudin
- Univ. Grenoble Alpes, SPINTEC, Grenoble F-38000, France
- CNRS, SPINTEC, Grenoble F-38000, France
- CEA, INAC-SPINTEC, Grenoble F-38000, France
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28
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Sala A, Zamborlini G, Menteş TO, Locatelli A. Fabrication of 2D Heterojunction in Graphene via Low Energy N2(+) Irradiation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5927-5931. [PMID: 26439586 DOI: 10.1002/smll.201501473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 08/14/2015] [Indexed: 06/05/2023]
Abstract
Substitutional doping in graphene is locally induced with very low energy nitrogen ions. Irradiated and nonirradiated areas exhibit different charge carrier densities and are separated by a sharp boundary, stable up to 750 °C. The way towards lithographic control of the electronic properties of graphene by ion irradiation is paved, providing a proof of principle for the fabrication of 2D graphene-based heterojunctions.
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Affiliation(s)
- Alessandro Sala
- Elettra-Sincrotrone Trieste S.C.p.A, S.S.14-km 163.5, Area Science Park Basovizza, 34149, Trieste, Italy
| | - Giovanni Zamborlini
- Department of Physics, University of Trieste, Via Valerio 2, 34127, Trieste, Italy
- Peter Grünberg Institute (PGI-6), Research Center Jülich, 52425, Jülich, Germany
| | - Tevfik Onur Menteş
- Elettra-Sincrotrone Trieste S.C.p.A, S.S.14-km 163.5, Area Science Park Basovizza, 34149, Trieste, Italy
| | - Andrea Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A, S.S.14-km 163.5, Area Science Park Basovizza, 34149, Trieste, Italy
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29
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Zamborlini G, Imam M, Patera LL, Menteş TO, Stojić N, Africh C, Sala A, Binggeli N, Comelli G, Locatelli A. Nanobubbles at GPa Pressure under Graphene. NANO LETTERS 2015; 15:6162-6169. [PMID: 26241631 DOI: 10.1021/acs.nanolett.5b02475] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We provide direct evidence that irradiation of a graphene membrane on Ir with low-energy Ar ions induces formation of solid noble-gas nanobubbles. Their size can be controlled by thermal treatment, reaching tens of nanometers laterally and height of 1.5 nm upon annealing at 1080 °C. Ab initio calculations show that Ar nanobubbles are subject to pressures reaching tens of GPa, their formation being driven by minimization of the energy cost of film distortion and loss of adhesion.
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Affiliation(s)
- Giovanni Zamborlini
- Department of Physics, University of Trieste , Via Valerio 2, I-34127 Trieste, Italy
- Peter Grünberg Institute (PGI-6) , Research Centre Jülich, 52425 Jülich, Germany
| | - Mighfar Imam
- Abdus Salam International Centre for Theoretical Physics , Strada Costiera 11, Trieste I-34151, Italy
| | - Laerte L Patera
- Department of Physics, University of Trieste , Via Valerio 2, I-34127 Trieste, Italy
- IOM-CNR Laboratorio TASC , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Tevfik Onur Menteş
- Elettra - Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Nataša Stojić
- Abdus Salam International Centre for Theoretical Physics , Strada Costiera 11, Trieste I-34151, Italy
- IOM-CNR Democritos , Trieste I-34151, Italy
| | - Cristina Africh
- IOM-CNR Laboratorio TASC , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Alessandro Sala
- Elettra - Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Nadia Binggeli
- Abdus Salam International Centre for Theoretical Physics , Strada Costiera 11, Trieste I-34151, Italy
- IOM-CNR Democritos , Trieste I-34151, Italy
| | - Giovanni Comelli
- Department of Physics, University of Trieste , Via Valerio 2, I-34127 Trieste, Italy
- IOM-CNR Laboratorio TASC , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
| | - Andrea Locatelli
- Elettra - Sincrotrone Trieste , S.S. 14 km 163.5 in AREA Science Park, Basovizza, I-34149 Trieste, Italy
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