1
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
2
|
Cojocariu I, Jugovac M, Locatelli A, Menteş TO. Resonant Auger spectromicroscopy in ultrathin Fe films on W(110). J Phys Condens Matter 2023; 35. [PMID: 37582382 DOI: 10.1088/1361-648x/acf0b0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 08/15/2023] [Indexed: 08/17/2023]
Abstract
L3M2,3M2,3Auger transition is measured near the L3resonance of ferromagnetic Fe films on W(110). The kinetic energies of the Auger peaks display the typical Raman behaviour for photon energies well below the absorption threshold, where the Auger energy follows the changes in the photon energy. Classical Auger behaviour with constant kinetic energy sets in at about 1.5 eV below the L3resonance independently from the number of Fe layers down to the monolayer thickness. Strong x-ray circular magnetic dichroism is observed at the L3edge in the entire L3M2,3M2,3Auger spectrum. Different Auger features originating from the final state with two 3p core holes show slight variations in the dichroic signal, which is attributed to the exchange interaction between the core holes and the valence band. Finally, XMCD-PEEM magnetic domain imaging using Auger electrons is demonstrated with a high level of contrast and lateral resolution approaching that of imaging with secondary photoelectrons.
Collapse
Affiliation(s)
- I Cojocariu
- Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5, 34149 Trieste, Italy
- Dipartimento di Fisica, Università degli studi di Trieste, Via A. Valerio 2, 34127 Trieste, Italy
| | - M Jugovac
- Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5, 34149 Trieste, Italy
| | - A Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5, 34149 Trieste, Italy
| | - T O Menteş
- Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14 km 163.5, 34149 Trieste, Italy
| |
Collapse
|
3
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
4
|
Schöbitz M, De Riz A, Martin S, Bochmann S, Thirion C, Vogel J, Foerster M, Aballe L, Menteş TO, Locatelli A, Genuzio F, Le-Denmat S, Cagnon L, Toussaint JC, Gusakova D, Bachmann J, Fruchart O. Erratum: Fast Domain Wall Motion Governed by Topology and Œrsted Fields in Cylindrical Magnetic Nanowires [Phys. Rev. Lett. 123, 217201 (2019)]. Phys Rev Lett 2020; 125:249901. [PMID: 33412077 DOI: 10.1103/physrevlett.125.249901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Indexed: 06/12/2023]
Abstract
This corrects the article DOI: 10.1103/PhysRevLett.123.217201.
Collapse
|
5
|
Slęzak M, Dróżdż P, Janus W, Nayyef H, Kozioł-Rachwał A, Szpytma M, Zając M, Menteş TO, Genuzio F, Locatelli A, Slęzak T. Correction: Fine tuning of ferromagnet/antiferromagnet interface magnetic anisotropy for field-free switching of antiferromagnetic spins. Nanoscale 2020; 12:19477. [PMID: 32959041 DOI: 10.1039/d0nr90207a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Correction for 'Fine tuning of ferromagnet/antiferromagnet interface magnetic anisotropy for field-free switching of antiferromagnetic spins' by M. Slęzak et al., Nanoscale, 2020, DOI: 10.1039/d0nr04193a.
Collapse
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
- CERIC-ERIC, 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.
| |
Collapse
|
6
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
7
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
8
|
Schöbitz M, De Riz A, Martin S, Bochmann S, Thirion C, Vogel J, Foerster M, Aballe L, Menteş TO, Locatelli A, Genuzio F, Le-Denmat S, Cagnon L, Toussaint JC, Gusakova D, Bachmann J, Fruchart O. Fast Domain Wall Motion Governed by Topology and Œrsted Fields in Cylindrical Magnetic Nanowires. Phys Rev Lett 2019; 123:217201. [PMID: 31809154 DOI: 10.1103/physrevlett.123.217201] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Indexed: 05/26/2023]
Abstract
While the usual approach to tailor the behavior of condensed matter and nanosized systems is the choice of material or finite-size or interfacial effects, topology alone may be the key. In the context of the motion of magnetic domain walls (DWs), known to suffer from dynamic instabilities with low mobilities, we report unprecedented velocities >600 m/s for DWs driven by spin-transfer torques in cylindrical nanowires made of a standard ferromagnetic material. The reason is the robust stabilization of a DW type with a specific topology by the Œrsted field associated with the current. This opens the route to the realization of predicted new physics, such as the strong coupling of DWs with spin waves above >600 m/s.
Collapse
Affiliation(s)
- M Schöbitz
- Univ. Grenoble Alpes, CNRS, CEA, Spintec, 38054 Grenoble, France
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Inorganic Chemistry, 91058 Erlangen, Germany
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - A De Riz
- Univ. Grenoble Alpes, CNRS, CEA, Spintec, 38054 Grenoble, France
| | - S Martin
- Univ. Grenoble Alpes, CNRS, CEA, Spintec, 38054 Grenoble, France
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - S Bochmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Inorganic Chemistry, 91058 Erlangen, Germany
| | - C Thirion
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - J Vogel
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - M Foerster
- Alba Synchrotron Light Facility, CELLS, 08290 Barcelona, Spain
| | - L Aballe
- Alba Synchrotron Light Facility, CELLS, 08290 Barcelona, Spain
| | - T O Menteş
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy
| | - A Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy
| | - F Genuzio
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, 34149 Trieste, Italy
| | - S Le-Denmat
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - L Cagnon
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - J C Toussaint
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France
| | - D Gusakova
- Univ. Grenoble Alpes, CNRS, CEA, Spintec, 38054 Grenoble, France
| | - J Bachmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Inorganic Chemistry, 91058 Erlangen, Germany
- Institute of Chemistry, Saint Petersburg State University, St. Petersburg 198504, Russia
| | - O Fruchart
- Univ. Grenoble Alpes, CNRS, CEA, Spintec, 38054 Grenoble, France
| |
Collapse
|
9
|
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. J Phys Condens Matter 2019; 31:445804. [PMID: 31392970 DOI: 10.1088/1361-648x/ab303c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
Affiliation(s)
- T Hajiri
- Department of Materials Physics, Nagoya University, Nagoya 464-8603, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
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 Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
11
|
Nevius MS, Wang F, Mathieu C, Barrett N, Sala A, Menteş TO, Locatelli A, Conrad EH. The bottom-up growth of edge specific graphene nanoribbons. Nano Lett 2014; 14:6080-6086. [PMID: 25254434 DOI: 10.1021/nl502942z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The discovery of ballistic transport in graphene grown on SiC(0001) sidewall trenches has sparked an intense effort to uncover the origin of this exceptional conductivity. How a ribbon's edge termination, width, and topography influence its transport is not yet understood. This work presents the first structural and electronic comparison of sidewall graphene grown with different edge terminations. We show that armchair and zigzag terminated ribbons, grown from SiC, have very different topographies and interact differently with the substrate, properties that are critical to device architecture in sidewall ribbon electronics.
Collapse
Affiliation(s)
- M S Nevius
- The Georgia Institute of Technology , Atlanta, Georgia 30332-0430, United States
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Rault JE, Menteş TO, Locatelli A, Barrett N. Reversible switching of in-plane polarized ferroelectric domains in BaTiO3(001) with very low energy electrons. Sci Rep 2014; 4:6792. [PMID: 25354723 PMCID: PMC4213810 DOI: 10.1038/srep06792] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/07/2014] [Indexed: 11/09/2022] Open
Abstract
The switchable bipolar ground state is at the heart of research into ferroelectrics for future, low-energy electronics. Polarization switching by an applied field is a complex phenomenon which depends on the initial domain ordering, defect concentration, electrical boundary conditions and charge screening. Injected free charge may also to be used to reversibly switch in-plane polarized domains. We show that the interaction between the initial domain order and the bulk screening provided by very low energy electrons switches the polarization without the collateral radiation damage which occurs when employing a beam of high energy electrons. Polarization switching during charge injection adds a new dimension to the multifunctionality of ferroelectric oxides.
Collapse
Affiliation(s)
- J E Rault
- Synchrotron-SOLEIL, BP 48, Saint-Aubin, F-91192 Gif sur Yvette CEDEX, France
| | - T O Menteş
- Elettra-Sincrotrone Trieste S.C.p.A.. Strada Statale 14 - km 163, 5 in AREA Science Park 34149 Basovizza, Trieste, Italy
| | - A Locatelli
- Elettra-Sincrotrone Trieste S.C.p.A.. Strada Statale 14 - km 163, 5 in AREA Science Park 34149 Basovizza, Trieste, Italy
| | - N Barrett
- CEA, DSM/IRAMIS/SPEC, F-91191 Gif-sur-Yvette Cedex, France
| |
Collapse
|
13
|
Menteş TO, Zamborlini G, Sala A, Locatelli A. Cathode lens spectromicroscopy: methodology and applications. Beilstein J Nanotechnol 2014; 5:1873-86. [PMID: 25383299 PMCID: PMC4222408 DOI: 10.3762/bjnano.5.198] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/25/2014] [Indexed: 05/28/2023]
Abstract
The implementation of imaging techniques with low-energy electrons at synchrotron laboratories allowed for significant advancement in the field of spectromicroscopy. The spectroscopic photoemission and low energy electron microscope, SPELEEM, is a notable example. We summarize the multitechnique capabilities of the SPELEEM instrument, reporting on the instrumental aspects and the latest developments on the technical side. We briefly review applications, which are grouped into two main scientific fields. The first one covers different aspects of graphene physics. In particular, we highlight the recent work on graphene/Ir(100). Here, SPELEEM was employed to monitor the changes in the electronic structure that occur for different film morphologies and during the intercalation of Au. The Au monolayer, which creeps under graphene from the film edges, efficiently decouples the graphene from the substrate lowering the Dirac energy from 0.42 eV to 0.1 eV. The second field combines magnetism studies at the mesoscopic length scale with self-organized systems featuring ordered nanostructures. This example highlights the possibility to monitor growth processes in real time and combine chemical characterization with X-ray magnetic circular dichroism-photoemission electron microscopy (XMCD-PEEM) magnetic imaging by using the variable photon polarization and energy available at the synchrotron source.
Collapse
Affiliation(s)
- T O Menteş
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
| | - G Zamborlini
- Department of Physics, University of Trieste, Via Valerio 2, Trieste 34137, Italy
- Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, 52425 Jülich, Germany
| | - A Sala
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
| | - A Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A., Basovizza, Trieste 34149, Italy
| |
Collapse
|
14
|
Montaigne F, Lacour D, Chioar IA, Rougemaille N, Louis D, Mc Murtry S, Riahi H, Burgos BS, Menteş TO, Locatelli A, Canals B, Hehn M. Size distribution of magnetic charge domains in thermally activated but out-of-equilibrium artificial spin ice. Sci Rep 2014; 4:5702. [PMID: 25029620 PMCID: PMC4100542 DOI: 10.1038/srep05702] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/26/2014] [Indexed: 11/09/2022] Open
Abstract
A crystal of emerging magnetic charges is expected in the phase diagram of the dipolar kagomé spin ice. An observation of charge crystallites in thermally demagnetized artificial spin ice arrays has been recently reported by S. Zhang and coworkers and explained through the thermodynamics of the system as it approaches a charge-ordered state. Following a similar approach, we have generated a partial order of magnetic charges in an artificial kagomé spin ice lattice made out of ferrimagnetic material having a Curie temperature of 475 K. A statistical study of the size of the charge domains reveals an unconventional sawtooth distribution. This distribution is in disagreement with the predictions of the thermodynamic model and is shown to be a signature of the kinetic process governing the remagnetization.
Collapse
Affiliation(s)
- F Montaigne
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| | - D Lacour
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| | - I A Chioar
- 1] CNRS, Institut NEEL, F-38042 Grenoble, France [2] Univ. Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
| | - N Rougemaille
- 1] CNRS, Institut NEEL, F-38042 Grenoble, France [2] Univ. Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
| | - D Louis
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| | - S Mc Murtry
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| | - H Riahi
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| | - B Santos Burgos
- Elettra-Sincrotrone Trieste S.C.p.A. S.S. 14 - km 163,5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
| | - 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
| | - B Canals
- 1] CNRS, Institut NEEL, F-38042 Grenoble, France [2] Univ. Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
| | - M Hehn
- Institut Jean Lamour, Université de Lorraine and CNRS, Vandoeuvre lès Nancy, F-54506, France
| |
Collapse
|
15
|
Stojić N, Menteş TO, Binggeli N. Self-organization in Pd/W(110): interplay between surface structure and stress. J Phys Condens Matter 2013; 25:355010. [PMID: 23920010 DOI: 10.1088/0953-8984/25/35/355010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
It has recently been shown that submonolayer Pd on W(110) forms highly ordered linear mesoscopic stripes at high temperatures. The stripes display an internal Pd superstructure with a nano-scale periodicity along the direction perpendicular to the periodicity of the stripes. The same type of superstructure is also observed in a wide range of temperatures below the stripe formation temperature. We present a combined experimental and theoretical study of this superstructure of Pd on W(110) and investigate its influence on the appearance of the linear mesoscopic stripes. By means of low-energy electron diffraction and low-energy electron microscopy we show that it has a far more peculiar dependence on temperature and coverage than expected from a regular surface reconstruction. Using density-functional theory, we model the Pd superstructures as periodic vacancy-line type configurations and investigate their energetics and elastic properties. From our calculated surface stresses and anisotropies for the vacancy-line configurations, and based on the continuum elasticity theory, we demonstrate quantitatively that the vacancy-line type of structure is a prerequisite for the formation of the linear mesoscopic stripes. Moreover, we show that the physics driving the formation of the internal superstructure is very similar to the one at play in forming the mesoscopic stripes themselves.
Collapse
Affiliation(s)
- N Stojić
- Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, Trieste I-34151, Italy. IOM-CNR Democritos, Trieste, I-34151, Italy.
| | | | | |
Collapse
|
16
|
Günther S, Liu H, Menteş TO, Locatelli A, Imbihl R. Spectromicroscopy of pulses transporting alkali metal in a surface reaction. Phys Chem Chem Phys 2013; 15:8752-64. [PMID: 23632422 DOI: 10.1039/c3cp44478c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The NO + H2 reaction on a potassium promoted Rh(110) surface is shown to sustain the formation of spatio-temporal periodic patterns leading to mass transport phenomena. The excitation of pulses and the mass transport mechanism are studied in the 10(-7) and 10(-6) mbar pressure range, with the potassium coverage varying between θK = 0.05 and θK = 0.12 ML. Using spectroscopic photoemission and spectroscopic low energy electron microscopy (SPELEEM) as well as related microprobe diffraction techniques, we show that the excitation mechanism comprises a cyclic structural transformation: K + O-coadsorbate → (2 × 1)-N → c(2 × 4)-2O,N → K + O coadsorbate. Laterally resolved spectroscopy demonstrates that potassium is accumulated in front of the nitrogen pulses, suggesting that adsorbed nitrogen acts as a diffusion barrier for potassium.
Collapse
Affiliation(s)
- S Günther
- TU München, Chemie Department, Lichtenbergstr. 4, D-85748 Garching, Germany
| | | | | | | | | |
Collapse
|
17
|
Alfè D, Pozzo M, Miniussi E, Günther S, Lacovig P, Lizzit S, Larciprete R, Burgos BS, Menteş TO, Locatelli A, Baraldi A. Fine tuning of graphene-metal adhesion by surface alloying. Sci Rep 2013; 3:2430. [PMID: 23938361 PMCID: PMC3741623 DOI: 10.1038/srep02430] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 07/29/2013] [Indexed: 11/11/2022] Open
Abstract
We show that bimetallic surface alloying provides a viable route for governing the interaction between graphene and metal through the selective choice of the elemental composition of the surface alloy. This concept is illustrated by an experimental and theoretical characterization of the properties of graphene on a model PtRu surface alloy on Ru(0001), with a concentration of Pt atoms in the first layer between 0 and 50%. The progressive increase of the Pt content determines the gradual detachment of graphene from the substrate, which results from the modification of the carbon orbital hybridization promoted by Pt. Alloying is also found to affect the morphology of graphene, which is strongly corrugated on bare Ru, but becomes flat at a Pt coverage of 50%. The method here proposed can be readily extended to several supports, thus opening the way to the conformal growth of graphene on metals and to a full tunability of the graphene-substrate interaction.
Collapse
Affiliation(s)
- D. Alfè
- Department of Earth Sciences, Department of Physics and Astronomy, TYC@UCL, and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- IOM-CNR, DEMOCRITOS National Simulation Centre, I-34100 Trieste, Italy
| | - M. Pozzo
- Department of Earth Sciences, Department of Physics and Astronomy, TYC@UCL, and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - E. Miniussi
- Physics Department and CENMAT, University of Trieste, Via Valerio 2, I-34127 Trieste, ITALY
- IOM-CNR, Laboratorio TASC, S.S. 14 Km 163.5, I-34149 Trieste, ITALY
| | - S. Günther
- Technische Universität München, Chemie Department, Physikalische Chemie mit Schwerpunkt Katalyse, Lichtenbergstr. 4, D-85748 Garching, Germany
| | - P. Lacovig
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34149 Trieste, ITALY
| | - S. Lizzit
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34149 Trieste, ITALY
| | - R. Larciprete
- CNR-Institute for Complex Systems, via Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - B. Santos Burgos
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34149 Trieste, ITALY
| | - T. O. Menteş
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34149 Trieste, ITALY
| | - A. Locatelli
- Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34149 Trieste, ITALY
| | - A. Baraldi
- Physics Department and CENMAT, University of Trieste, Via Valerio 2, I-34127 Trieste, ITALY
- IOM-CNR, Laboratorio TASC, S.S. 14 Km 163.5, I-34149 Trieste, ITALY
| |
Collapse
|
18
|
Miniussi E, Pozzo M, Baraldi A, Vesselli E, Zhan RR, Comelli G, Menteş TO, Niño MA, Locatelli A, Lizzit S, Alfè D. Thermal stability of corrugated epitaxial graphene grown on Re(0001). Phys Rev Lett 2011; 106:216101. [PMID: 21699318 DOI: 10.1103/physrevlett.106.216101] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Indexed: 05/31/2023]
Abstract
We report on a novel approach to determine the relationship between the corrugation and the thermal stability of epitaxial graphene grown on a strongly interacting substrate. According to our density functional theory calculations, the C single layer grown on Re(0001) is strongly corrugated, with a buckling of 1.6 Å, yielding a simulated C 1s core level spectrum which is in excellent agreement with the experimental one. We found that corrugation is closely knit with the thermal stability of the C network: C-C bond breaking is favored in the strongly buckled regions of the moiré cell, though it requires the presence of diffusing graphene layer vacancies.
Collapse
Affiliation(s)
- E Miniussi
- Physics Department and CENMAT, University of Trieste, Via Valerio 2, I-34127 Trieste, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Ilgaz D, Nievendick J, Heyne L, Backes D, Rhensius J, Moore TA, Niño MA, Locatelli A, Menteş TO, Schmidsfeld AV, Bieren AV, Krzyk S, Heyderman LJ, Kläui M. Domain-wall depinning assisted by pure spin currents. Phys Rev Lett 2010; 105:076601. [PMID: 20868064 DOI: 10.1103/physrevlett.105.076601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Indexed: 05/29/2023]
Abstract
We study the depinning of domain walls by pure diffusive spin currents in a nonlocal spin valve structure based on two ferromagnetic Permalloy elements with copper as the nonmagnetic spin conduit. The injected spin current is absorbed by the second Permalloy structure with a domain wall, and from the dependence of the wall depinning field on the spin current density we find an efficiency of 6×10{-14} T/(A/m{2}), which is more than an order of magnitude larger than for conventional current induced domain-wall motion. Theoretically we find that this high efficiency arises from the surface torques exerted by the absorbed spin current that lead to efficient depinning.
Collapse
Affiliation(s)
- D Ilgaz
- Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Menteş TO, Locatelli A, Aballe L, Bauer E. Stress induced stripe formation in Pd/W(110). Phys Rev Lett 2008; 101:085701. [PMID: 18764637 DOI: 10.1103/physrevlett.101.085701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/12/2008] [Indexed: 05/26/2023]
Abstract
A stress-induced stripe phase of submonolayer Pd on W(110) is observed by low-energy electron microscopy. The temperature dependence of the pattern is explained by the change both in the boundary free energy and elastic relaxation energy due to the increasing boundary width. The stripes are shown to disorder when the correlation length of the condensed phase becomes comparable to its period, while the condensate to lattice-gas transition takes place at a higher temperature, as revealed by low-energy electron diffraction.
Collapse
Affiliation(s)
- T O Menteş
- Sincrotrone Trieste S.C.p.A., Basovizza-Trieste 34012, Italy
| | | | | | | |
Collapse
|
21
|
De Ninno G, Allaria E, Coreno M, Curbis F, Danailov MB, Karantzoulis E, Locatelli A, Menteş TO, Nino MA, Spezzani C, Trovò M. Generation of ultrashort coherent vacuum ultraviolet pulses using electron storage rings: a new bright light source for experiments. Phys Rev Lett 2008; 101:053902. [PMID: 18764393 DOI: 10.1103/physrevlett.101.053902] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 04/02/2008] [Indexed: 05/26/2023]
Abstract
We demonstrate for the first time that seeded harmonic generation on electron storage rings can produce coherent optical pulses in the vacuum ultraviolet spectral range. The experiment is performed at Elettra, where coherent pulses are generated at 132 nm, with a duration of about 100 fs. The light source has a repetition rate of 1 kHz and adjustable polarization; it is very bright, with a peak power several orders of magnitude above that of spontaneous synchrotron radiation. Owing to high stability, the source is used in a test photoemission electron microscopy experiment. We anticipate that seeded harmonic generation on storage rings can lead to unprecedented developments in time-resolved femtosecond spectroscopy and microscopy.
Collapse
Affiliation(s)
- G De Ninno
- Physics Department, Nova Gorica University, Nova Gorica, SI-5000 Slovenia and Sincrotrone Trieste, Trieste, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Menteş TO, Sánchez-Hanke C, Kao CC. Reconstruction of magnetization density in two-dimensional samples from soft X-ray speckle patterns using the multiple-wavelength anomalous diffraction method. J Synchrotron Radiat 2002; 9:90-95. [PMID: 11872929 DOI: 10.1107/s0909049502001310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2001] [Accepted: 01/21/2002] [Indexed: 05/23/2023]
Abstract
A non-destructive technique for imaging magnetic domains in thin films and two-dimensional magnetic structures using coherent soft X-ray scattering and the multiple-wavelength anomalous diffraction method (MAD) is proposed. The method exploits the strong energy dependence in the magnetic scattering amplitude for 3d transition metals near the L(2,3) absorption edges and 4f elements near the M(4,5) absorption edges. The phase information required in the reconstruction algorithm is derived from the interference between the charge and magnetic scattering amplitudes. Magnetic speckle patterns from the magnetic domain distribution in an artificially defined Fe thin film are used to demonstrate this reconstruction algorithm. Circularly and linearly polarized incident light are examined separately to investigate the effect of polarization on the capability of the method.
Collapse
Affiliation(s)
- T O Menteş
- NSLS, Brookhaven National Laboratory, Upton, NY 11973, USA.
| | | | | |
Collapse
|