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Averyanov DV, Sokolov IS, Taldenkov AN, Parfenov OE, Kondratev OA, Tokmachev AM, Storchak VG. Emerging 2D Ferromagnetism in Graphenized GdAlSi. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2402189. [PMID: 38973106 DOI: 10.1002/smll.202402189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 06/18/2024] [Indexed: 07/09/2024]
Abstract
2D magnets are expected to give new insights into the fundamentals of magnetism, host novel quantum phases, and foster development of ultra-compact spintronics. However, the scarcity of 2D magnets often makes a bottleneck in the research efforts, prompting the search for new magnetic systems and synthetic routes. Here, an unconventional approach is adopted to the problem, graphenization - stabilization of layered honeycomb materials in the 2D limit. Tetragonal GdAlSi, stable in the bulk, in ultrathin films gives way to its layered counterpart - graphene-like anionic AlSi layers coupled to Gd cations. A series of inch-scale films of layered GdAlSi on silicon is synthesized, down to a single monolayer, by molecular beam epitaxy. Graphenization induces an easy-plane ferromagnetic order in GdAlSi. The magnetism is controlled by low magnetic fields, revealing its 2D nature. Remarkably, it exhibits a non-monotonic evolution with the number of monolayers. The results provide a fresh platform for research on 2D magnets by design.
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Affiliation(s)
- Dmitry V Averyanov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Ivan S Sokolov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Oleg E Parfenov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Oleg A Kondratev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow, 123182, Russia
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Averyanov DV, Sokolov IS, Taldenkov AN, Parfenov OE, Larionov KV, Sorokin PB, Kondratev OA, Tokmachev AM, Storchak VG. Engineering of a Layered Ferromagnet via Graphitization: An Overlooked Polymorph of GdAlSi. J Am Chem Soc 2024; 146:15761-15770. [PMID: 38825888 DOI: 10.1021/jacs.4c01472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Layered magnets are stand-out materials because of their range of functional properties that can be controlled by external stimuli. Regretfully, the class of such compounds is rather narrow, prompting the search for new members. Graphitization─stabilization of layered graphitic structures in the 2D limit─is being discussed for cubic materials. We suggest the phenomenon to extend beyond cubic structures; it can be employed as a viable route to a variety of layered materials. Here, the idea of graphitization is put into practice to produce a new layered magnet, GdAlSi. The honeycomb material, based on graphene-like layers AlSi, is studied both experimentally and theoretically. Epitaxial films of GdAlSi are synthesized on silicon; the critical thickness for the stability of the layered polymorph is around 20 monolayers. Notably, the layered polymorph of GdAlSi demonstrates ferromagnetism, in contrast to the nonlayered, tetragonal polymorph. The ferromagnetism is further supported by electron transport measurements revealing negative magnetoresistance and the anomalous Hall effect. The results show that graphitization can be a powerful tool in the design of functional layered materials.
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Affiliation(s)
- Dmitry V Averyanov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Ivan S Sokolov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Oleg E Parfenov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Konstantin V Larionov
- Laboratory of Digital Materials Science, National University of Science and Technology MISIS, Leninskiy prospect 4, 119049 Moscow, Russia
| | - Pavel B Sorokin
- Laboratory of Digital Materials Science, National University of Science and Technology MISIS, Leninskiy prospect 4, 119049 Moscow, Russia
| | - Oleg A Kondratev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
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Pecoraro A, Muñoz-García AB, Sannino GV, Veneri PD, Pavone M. Exotic hexagonal NaCl atom-thin layer on methylammonium lead iodide perovskite: new hints for perovskite solar cells from first-principles calculations. Phys Chem Chem Phys 2024; 26:1602-1607. [PMID: 38165025 DOI: 10.1039/d3cp02712k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Alkali halides are simple inorganic compounds extensively used as surface modifiers in optoelectronic devices. In perovskite solar cells (PSCs), they act as interlayers between the light absorber material and the charge selective layers improving their contact quality. They introduce surface dipoles that enable the fine tuning of the relative band alignment and passivate surface defects, a well-known drawback of hybrid organic-inorganic perovskites, that is responsible for most of the issues hampering the long-term performances. Reducing the thickness of such salt-based insulating layer might be beneficial in terms of charge transfer between the perovskite and the electron/hole transport layers. In this context, here we apply density functional theory (DFT) to characterize the structure and the electronic features of atom-thin layers of NaCl adsorbed on the methylammonium lead iodide (MAPI) perovskite. We analyze two different models of MAPI surface terminations and find unexpected structural reconstructions arising at the interface. Unexpectedly, we find an exotic honeycomb-like structuring of the salt, also recently observed in experiments on a diamond substrate. We also investigate how the salt affects the perovskite electronic properties that are key to control the charge dynamics at the interface. Moreover, we also assess the salt ability to improve the defect tolerance of the perovskite surface. With these results, we derive new hints regarding the potential benefits of using an atom-thin layer of alkali halides in PSCs.
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Affiliation(s)
- Adriana Pecoraro
- Department of Physics "E. Pancini", University of Naples Federico II, Napoli, Italy.
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
| | - Ana B Muñoz-García
- Department of Physics "E. Pancini", University of Naples Federico II, Napoli, Italy.
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
| | - Gennaro V Sannino
- Department of Chemical Sciences, University of Naples Federico II, Napoli, Italy
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Portici (NA), Italy
| | - Paola Delli Veneri
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Portici (NA), Italy
| | - Michele Pavone
- INSTM-GISEL, National Interuniversity Consortium of Materials Science and Technology (INSTM), Florence, Italy.
- Department of Chemical Sciences, University of Naples Federico II, Napoli, Italy
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Ma H, Wang X, Wang C, Zhang H, Ma X, Deng W, Chen R, Cao T, Chai Y, He Y, Ji W, Li R, Chen J, Ji J, Rao W, Xue M. Metal Halides for High-Capacity Energy Storage. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205071. [PMID: 36366943 DOI: 10.1002/smll.202205071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/15/2022] [Indexed: 06/16/2023]
Abstract
High-capacity electrochemical energy storage systems are more urgently needed than ever before with the rapid development of electric vehicles and the smart grid. The most efficient way to increase capacity is to develop electrode materials with low molecular weights. The low-cost metal halides are theoretically ideal cathode materials due to their advantages of high capacity and redox potential. However, their cubic structure and large energy barrier for deionization impede their rechargeability. Here, the reversibility of potassium halides, lithium halides, sodium halides, and zinc halides is achieved through decreasing their dimensionality by the strong π-cation interactions between metal cations and reduced graphene oxide (rGO). Especially, the energy densities of KI-, KBr-, and KCl-based materials are 722.2, 635.0, and 739.4 Wh kg-1 , respectively, which are higher than those of other cathode materials for potassium-ion batteries. In addition, the full-cell with 2D KI/rGO as cathode and graphite as anode demonstrates a lifespan of over 150 cycles with a considerable capacity retention of 57.5%. The metal halides-based electrode materials possess promising application prospects and are worthy of more in-depth researches.
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Affiliation(s)
- Hui Ma
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xusheng Wang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Cong Wang
- Department of Physics, Renmin University of China, Beijing, 100872, China
| | - Huanrong Zhang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinlei Ma
- Department of Chemistry, Renmin University of China, Beijing, 100872, China
| | - Wenjun Deng
- School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
| | - Ruoqi Chen
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tianqi Cao
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yuqiao Chai
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yonglin He
- Department of Chemistry, Renmin University of China, Beijing, 100872, China
| | - Wei Ji
- Department of Physics, Renmin University of China, Beijing, 100872, China
| | - Rui Li
- School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
| | - Jitao Chen
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Junhui Ji
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wei Rao
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Mianqi Xue
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
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