1
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Nakashima K, Takahama H, Yoshida M, Yamaguchi K, Hata K. Synthesis of BaTiO 3-CaTiO 3 and BaTiO 3-SrTiO 3 Core-Shell Nanocubes via the Surface Reconstruction of BaTiO 3 Nanocubes. Inorg Chem 2024; 63:44-49. [PMID: 38099808 DOI: 10.1021/acs.inorgchem.3c02935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
BaTiO3-CaTiO3 and SrTiO3-BaTiO3 core-shell nanocubes were synthesized through the surface reconstruction of BaTiO3 nanocubes, which involved the reaction of titanium oxide with Ca(OH)2, Sr(OH)2, or Sr(OH)2·8H2O in water at 100 °C. The core-shell structure comprised a BaTiO3 nanocube core and a CaTiO3 or SrTiO3 shell. The outermost layer with a perovskite structure also comprised CaTiO3 or SrTiO3, and its thickness was several hundred picometers. The thinnest layer was constructed of only one layer of CaTiO3 or SrTiO3. This is the first presented work on a core-shell nanocube with the outermost layer consisting of only CaTiO3 or SrTiO3 surrounding the BaTiO3 nanocube. The shells of CaTiO3 and SrTiO3 comprise a layer thickness of only one unit cell of ∼0.4 nm (400 pm). Thus, we demonstrate new research on nanocube surfaces on the picometer scale.
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Affiliation(s)
- Kouichi Nakashima
- Department of Materials Science and Engineering, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
| | - Hikaru Takahama
- Department of Materials Science and Engineering, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
| | - Mikitaka Yoshida
- Department of Materials Science and Engineering, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
| | - Ken Yamaguchi
- Samsung Device Solutions R&D Japan, Samsung Japan Coorporation, 2-1-11 Senba-nishi, Minoh, Osaka 562-0036, Japan
| | - Kotaro Hata
- Samsung Device Solutions R&D Japan, Samsung Japan Coorporation, 2-1-11 Senba-nishi, Minoh, Osaka 562-0036, Japan
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2
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Song C, Bo T, Liu X, Guo P, Meng S, Wu K. Local Kondo scattering in 4d-electron RuO x nanoclusters on atomically-resolved ultrathin SrRuO 3 films. Phys Chem Chem Phys 2021; 23:22526-22531. [PMID: 34590637 DOI: 10.1039/d1cp02738g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Perovskite SrRuO3 is a unique 4d transition metal oxide with coexisting spin-orbit coupling (SOC) and electron-electron correlation. However, the intrinsic, non-reconstructed surface structure of SrRuO3 has not been reported so far. Here we report an atomic imaging of the non-reconstructed, SrO-terminated SrRuO3 surface by scanning tunneling microscopy/spectroscopy. Moreover, a Kondo resonant behavior is revealed in RuOx clusters located on top of the nonmagnetic SrO surface layer. The density functional theory calculations confirm that RuOx clusters possess localized 4d-electron-involved spin moments and hybridize with the conduction electrons in the metal host, resulting in the appearance of the Kondo resonance features around the Fermi level. Our work demonstrates that artificially-engineered transition metal oxides provide new opportunities to explore the Kondo physics in 4d multi-orbital systems.
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Affiliation(s)
- Chuangye Song
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China. .,Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Tao Bo
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China. .,Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xin Liu
- Swiss Light Source, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Pengjie Guo
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China. .,Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Sheng Meng
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China. .,Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kehui Wu
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China. .,Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Li Z, Liu X, Jiang J, Mi W, Bai H. Electric field induced reversal of spin polarization, magnetic anisotropy and tailored Dzyaloshinskii-Moriya interaction in underoxidized SrRuO 3/SrTiO 3 heterostructures. Phys Chem Chem Phys 2021; 23:3008-3018. [PMID: 33480932 DOI: 10.1039/d0cp06362b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electric field tailored magnetic properties of the perovskite-type oxide heterostructures are important in spintronic devices with low energy consumption and small size. Here, the electric field modulated magnetic properties of underoxidized SrRuO3 (SRO)/SrTiO3 (STO) heterostructures are investigated using first-principles calculations. The spin polarization of underoxidized SRO/STO heterostructures turns from negative to positive as the electric field changes from -0.2 to 0.2 V nm-1. The underoxidized SRO/STO heterostructure with 7 SRO atomic layers turns from perpendicular magnetic anisotropy to in-plane magnetic anisotropy as the electric field turns from -0.2 to 0.2 V nm-1, which can be attributed to the in-plane dx2-y2 and out-of-plane dxz, dyz orbitals. The Dzyaloshinskii-Moriya interaction of underoxidized SRO/STO heterostructures can also be effectively tailored using an electric field. These results indicate that the use of electric field is an effective method to modulate magnetic properties of perovskite-type oxide heterostructures, which is beneficial for the development of the high-performance spintronic devices.
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Affiliation(s)
- Zengjie Li
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
| | - Xiang Liu
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
| | - Jiawei Jiang
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
| | - Wenbo Mi
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
| | - Haili Bai
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin 300354, China.
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4
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Lee HG, Wang L, Si L, He X, Porter DG, Kim JR, Ko EK, Kim J, Park SM, Kim B, Wee ATS, Bombardi A, Zhong Z, Noh TW. Atomic-Scale Metal-Insulator Transition in SrRuO 3 Ultrathin Films Triggered by Surface Termination Conversion. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905815. [PMID: 31830343 DOI: 10.1002/adma.201905815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/12/2019] [Indexed: 06/10/2023]
Abstract
The metal-insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO3 ultrathin films is reported. Uniform and effective termination engineering at the SrRuO3 (001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO2 , a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO3 monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision.
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Affiliation(s)
- Han Gyeol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Lingfei Wang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Liang Si
- Key Laboratory of Magnetic Materials and Devices & Zhejiang Province, Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- Institut für Festkörperphysik, Vienna, 1040, Austria
| | - Xiaoyue He
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
- Songshan Lake Materials Laboratory, Dongguan, 523808, P. R. China
| | - Daniel G Porter
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jinkwon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung Min Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, Singapore, 117542, Singapore
| | - Alessandro Bombardi
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Zhicheng Zhong
- Key Laboratory of Magnetic Materials and Devices & Zhejiang Province, Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, P. R. China
- China Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
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5
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Huang BC, Yu P, Chu YH, Chang CS, Ramesh R, Dunin-Borkowski RE, Ebert P, Chiu YP. Atomically Resolved Electronic States and Correlated Magnetic Order at Termination Engineered Complex Oxide Heterointerfaces. ACS NANO 2018; 12:1089-1095. [PMID: 29384356 DOI: 10.1021/acsnano.7b06004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We map electronic states, band gaps, and interface-bound charges at termination-engineered BiFeO3/La0.7Sr0.3MnO3 interfaces using atomically resolved cross-sectional scanning tunneling microscopy. We identify a delicate interplay of different correlated physical effects and relate these to the ferroelectric and magnetic interface properties tuned by engineering the atomic layer stacking sequence at the interfaces. This study highlights the importance of a direct atomically resolved access to electronic interface states for understanding the intriguing interface properties in complex oxides.
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Affiliation(s)
- Bo-Chao Huang
- Department of Physics, National Taiwan University , Taipei 106, Taiwan
- Institute of Physics, Academia Sinica , Taipei 105, Taiwan
| | - Pu Yu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, and Collaborative Innovation Center of Quantum Matter , Beijing 100084, China
- RIKEN Center for Emergent Matter Science (CEMS) , Wako, Saitama 351-0198, Japan
| | - Y H Chu
- Institute of Physics, Academia Sinica , Taipei 105, Taiwan
- Department of Materials Science and Engineering, National Chiao Tung University , Hsinchu 300, Taiwan
| | | | - Ramamoorthy Ramesh
- Department of Physics, University of California , Berkeley, California 94720, United States
| | | | - Philipp Ebert
- Peter Grünberg Institut, Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
| | - Ya-Ping Chiu
- Department of Physics, National Taiwan University , Taipei 106, Taiwan
- Institute of Physics, Academia Sinica , Taipei 105, Taiwan
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6
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Designing functionality in perovskite thin films using ion implantation techniques: Assessment and insights from first-principles calculations. Sci Rep 2017; 7:11166. [PMID: 28894129 PMCID: PMC5593984 DOI: 10.1038/s41598-017-11158-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/18/2017] [Indexed: 11/09/2022] Open
Abstract
Recent experimental findings have demonstrated that low doses of low energy helium ions can be used to tailor the structural and electronic properties of single crystal films. These initial studies have shown that changes to lattice expansion were proposed to be the direct result of chemical pressure originating predominantly from the implanted He applying chemical pressure at interstitial sites. However, the influence of possible secondary knock-on damage arising from the He atoms transferring energy to the lattice through nuclear-nuclear collision with the crystal lattice remains largely unaddressed. Here, we study SrRuO3 to provide a comprehensive examination of the impact of common defects on structural and electronic properties. We found that, while interstitial He can modify the properties, a dose significantly larger than those reported in experimental studies would be required. Our study suggests that true origin of the observed changes is from combination of secondary defects created during He implantation. Of particular importance, we observe that different defect types can generate greatly varied local electronic structures and that the formation energies and migration energy barriers vary by defect type. Thus, we may have identified a new method of selectively inducing controlled defect complexes into single crystal materials.
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Shin YJ, Kim Y, Kang SJ, Nahm HH, Murugavel P, Kim JR, Cho MR, Wang L, Yang SM, Yoon JG, Chung JS, Kim M, Zhou H, Chang SH, Noh TW. Interface Control of Ferroelectricity in an SrRuO 3 /BaTiO 3 /SrRuO 3 Capacitor and its Critical Thickness. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1602795. [PMID: 28256752 DOI: 10.1002/adma.201602795] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 12/21/2016] [Indexed: 06/06/2023]
Abstract
The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO3 /BaTiO3 /SrRuO3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO2 -BaO and SrO-TiO2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.
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Affiliation(s)
- Yeong Jae Shin
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yoonkoo Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung-Jin Kang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Ho-Hyun Nahm
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Pattukkannu Murugavel
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Myung Rae Cho
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Lingfei Wang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sang Mo Yang
- Department of Physics, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Jong-Gul Yoon
- Department of Physics, University of Suwon, Hwaseong, Gyunggi-do, 18323, Republic of Korea
| | - Jin-Seok Chung
- Department of Physics, Soongsil University, Seoul, 06978, Republic of Korea
| | - Miyoung Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hua Zhou
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Seo Hyoung Chang
- Department of Physics, Pukyong National University, Busan, 48513, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
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8
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Nonnenmann SS. A hot tip: imaging phenomena using in situ multi-stimulus probes at high temperatures. NANOSCALE 2016; 8:3164-3180. [PMID: 26795921 DOI: 10.1039/c5nr08172f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Accurate high temperature characterization of materials remains a critical challenge to the continued advancement of various important energy, nuclear, electronic, and aerospace applications. Future experimental studies must assist these communities to progress past empiricism and derive deliberate, predictable designs of material classes functioning within active, extreme environments. Successful realization of systems ranging from fuel cells and batteries to electromechanical nanogenerators and turbines requires a dynamic understanding of the excitation, surface-mediated, and charge transfer phenomena which occur at heterophase interfaces (i.e. vapor-solid, liquid-solid, solid-solid) and impact overall performance. Advancing these frontiers therefore necessitates in situ (operando) characterization methods capable of resolving, both spatially and functionally, the coherence between these complex, collective excitations, and their respective response dynamics, through studies within the operating regime. This review highlights recent developments in scanning probe microscopy in performing in situ imaging at high elevated temperatures. The influence of and evolution from vacuum-based electron and tunneling microscopy are briefly summarized and discussed. The scope includes the use of high temperature imaging to directly observe critical phase transition, electronic, and electrochemical behavior under dynamic temperature settings, thus providing key physical parameters. Finally, both challenges and directions in combined instrumentation are proposed and discussed towards the end.
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Affiliation(s)
- Stephen S Nonnenmann
- Department of Mechanical and Industrial Engineering, University of Massachusetts-Amherst, 219 Engineering Laboratory I, 160 Governors Drive, Amherst, MA 01003-2210, USA.
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9
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Barrejón M, Gómez-Escalonilla MJ, Fierro JLG, Prieto P, Carrillo JR, Rodríguez AM, Abellán G, López-Escalante MC, Gabás M, López-Navarrete JT, Langa F. Modulation of the exfoliated graphene work function through cycloaddition of nitrile imines. Phys Chem Chem Phys 2016; 18:29582-29590. [DOI: 10.1039/c6cp05285a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
1,3-Dipolar cycloaddition between nitrile imines and graphene is studied. The work function of functionalized-graphene depends on the nature of functionalization.
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Affiliation(s)
- Myriam Barrejón
- Universidad de Castilla-La Mancha
- Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL)
- Toledo
- Spain
| | - María J. Gómez-Escalonilla
- Universidad de Castilla-La Mancha
- Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL)
- Toledo
- Spain
| | | | - Pilar Prieto
- Departamento de Química Orgánica
- Inorgánica y Bioquímica
- Facultad de Ciencias y Tecnologías Químicas
- Universidad de Castilla-La Mancha
- Campus Universitario
| | - José R. Carrillo
- Departamento de Química Orgánica
- Inorgánica y Bioquímica
- Facultad de Ciencias y Tecnologías Químicas
- Universidad de Castilla-La Mancha
- Campus Universitario
| | - Antonio M. Rodríguez
- Departamento de Química Orgánica
- Inorgánica y Bioquímica
- Facultad de Ciencias y Tecnologías Químicas
- Universidad de Castilla-La Mancha
- Campus Universitario
| | - Gonzalo Abellán
- Department of Chemistry and Pharmacy and Institute of Advanced Materials and Processes (ZMP)
- Friedrich Alexander University Erlangen-Nürnberg
- Henkestrasse
- 42
- 91054 Erlangen and Dr.-Mack Strasse 81
| | - Ma Cruz López-Escalante
- Unidad de Nanotecnología - The Nanotech Unit Dpto. Ingeniería Química
- Lab. Materiales & Superficies
- Universidad de Málaga
- 29071 Málaga
- Spain
| | - Mercedes Gabás
- Unidad de Nanotecnología - The Nanotech Unit Dpto. Física Aplicada I
- Lab. Materiales & Superficies
- Universidad de Málaga
- 29071 Málaga
- Spain
| | | | - Fernando Langa
- Universidad de Castilla-La Mancha
- Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL)
- Toledo
- Spain
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10
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Tselev A, Vasudevan RK, Gianfrancesco AG, Qiao L, Ganesh P, Meyer TL, Lee HN, Biegalski MD, Baddorf AP, Kalinin SV. Surface Control of Epitaxial Manganite Films via Oxygen Pressure. ACS NANO 2015; 9:4316-4327. [PMID: 25758864 DOI: 10.1021/acsnano.5b00743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The trend to reduce device dimensions demands increasing attention to atomic-scale details of structure of thin films as well as to pathways to control it. This is of special importance in the systems with multiple competing interactions. We have used in situ scanning tunneling microscopy to image surfaces of La5/8Ca3/8MnO3 films grown by pulsed laser deposition. The atomically resolved imaging was combined with in situ angle-resolved X-ray photoelectron spectroscopy. We find a strong effect of the background oxygen pressure during deposition on structural and chemical features of the film surface. Deposition at 50 mTorr of O2 leads to mixed-terminated film surfaces, with B-site (MnO2) termination being structurally imperfect at the atomic scale. A relatively small reduction of the oxygen pressure to 20 mTorr results in a dramatic change of the surface structure leading to a nearly perfectly ordered B-site terminated surface with only a small fraction of A-site (La,Ca)O termination. This is accompanied, however, by surface roughening at a mesoscopic length scale. The results suggest that oxygen has a strong link to the adatom mobility during growth. The effect of the oxygen pressure on dopant surface segregation is also pronounced: Ca surface segregation is decreased with oxygen pressure reduction.
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Affiliation(s)
- Alexander Tselev
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Rama K Vasudevan
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | | | - Liang Qiao
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - P Ganesh
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Tricia L Meyer
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Ho Nyung Lee
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | | | - Arthur P Baddorf
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Sergei V Kalinin
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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11
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Liu X, Li H, Chen Y, Jin Q, Ren K, Ji J. Mixed-charge nanoparticles for long circulation, low reticuloendothelial system clearance, and high tumor accumulation. Adv Healthc Mater 2014; 3:1439-47. [PMID: 24550205 DOI: 10.1002/adhm.201300617] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/29/2014] [Indexed: 01/06/2023]
Abstract
Mixed-charge zwitterionic surface modification shows great potential as a simple strategy to fabricate nanoparticle (NP) surfaces that are nonfouling. Here, the in vivo fate of 16 nm mixed-charge gold nanoparticles (AuNPs) is investigated, coated with mixed quaternary ammonium and sulfonic groups. The results show that mixed-charge AuNPs have a much longer blood half-life (≈30.6 h) than do poly(ethylene glycol) (PEG, M¯w = 2000) -coated AuNPs (≈6.65 h) and they accumulate in the liver and spleen far less than do the PEGylated AuNPs. Using transmission electron microscopy, it is further confirmed that the mixed-charge AuNPs have much lower uptake and different existing states in liver Kupffer cells and spleen macrophages one month after injection compared with the PEGylated AuNPs. Moreover, these mixed-charge AuNPs do not cause appreciable toxicity at this tested dose to mice in a period of 1 month as evidenced by histological examinations. Importantly, the mixed-charge AuNPs have higher accumulation and slower clearance in tumors than do PEGylated AuNPs for times of 24-72 h. Results from this work show promise for effectively designing tumor-targeting NPs that can minimize reticuloendothelial system clearance and circulate for long periods by using a simple mixed-charge strategy.
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Affiliation(s)
- Xiangsheng Liu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
| | - Huan Li
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
| | - Yangjun Chen
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
| | - Qiao Jin
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
| | - Kefeng Ren
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
| | - Jian Ji
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization; Department of Polymer Science and Engineering; Zhejiang University; Hangzhou 310027 China
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Bern F, Ziese M, Setzer A, Pippel E, Hesse D, Vrejoiu I. Structural, magnetic and electrical properties of SrRuO3 films and SrRuO3/SrTiO3 superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:496003. [PMID: 24184982 DOI: 10.1088/0953-8984/25/49/496003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
SrRuO3 films and SrRuO3/SrTiO3 superlattices grown on SrTiO3(001) were studied by structural, magnetic, magnetoresistance and Hall effect measurements. The superlattices showed heteroepitaxial growth with coherent interfaces and a Ru/Ti diffusion region of 1-1.5 unit cells. The resistivity had metallic character above a critical thickness of 3-4 unit cells, becoming insulating below. There was no hint of conduction processes along the interfaces. Both magnetization and magnetoresistance measurements showed an increase of the magnetic anisotropy, consistent with magnetostriction effects. The magnetostriction coefficient was estimated as λ100 ∼ 1.4 × 10(-4). Three unit cell thick SrRuO3 layers in SrRuO3/SrTiO3 superlattices were found to have tetragonal crystal symmetry, as deduced from the sign change of the anomalous Hall constant.
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Affiliation(s)
- F Bern
- Division of Superconductivity and Magnetism, Faculty of Physics and Geosciences, University of Leipzig, D-04103 Leipzig, Germany
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Tselev A, Ganesh P, Qiao L, Siemons W, Gai Z, Biegalski MD, Baddorf AP, Kalinin SV. Oxygen control of atomic structure and physical properties of SrRuO3 surfaces. ACS NANO 2013; 7:4403-4413. [PMID: 23570268 DOI: 10.1021/nn400923n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Complex oxide thin films and heterostructures have become one of the foci for condensed matter physics research due to a broad variety of properties they exhibit. Similar to the bulk, properties of oxide surfaces can be expected to be strongly affected by oxygen stoichiometry. Here we explore the coupling between atomic structure and physical properties of SrRuO3 (SRO), one of the most well-studied oxide materials. We perform a detailed in situ and ex situ experimental investigation of the surfaces of SRO thin films using a combination of scanning tunneling microscopy (STM), X-ray and ultraviolet photoelectron spectroscopy, SQUID magnetometry, and magnetotransport measurements, as well as ab initio modeling. A number of remarkable linear surface reconstructions were observed by STM and interpreted as oxygen adatoms, favorably adsorbed in a regular rectangular or zigzag patterns. The degree of oxygen coverage and different surface patterns change the work function of the thin films, and modify local electronic and magnetic properties of the topmost atomic layer. The ab initio modeling reveals that oxygen adatoms possess frustrated local spin moments with possible spin-glass behavior of the surface covered by adsorbed oxygen. Additionally, the modeling indicates presence of a pseudo gap on the topmost SrO layer on pristine SrO-terminated surface, suggesting possibility for realization of a surface half-metallic film.
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Affiliation(s)
- Alexander Tselev
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
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Callori SJ, Gabel J, Su D, Sinsheimer J, Fernandez-Serra MV, Dawber M. Ferroelectric PbTiO3/SrRuO3 superlattices with broken inversion symmetry. PHYSICAL REVIEW LETTERS 2012; 109:067601. [PMID: 23006304 DOI: 10.1103/physrevlett.109.067601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Indexed: 06/01/2023]
Abstract
We have fabricated PbTiO3/SrRuO3 superlattices with ultrathin SrRuO3 layers. Because of the superlattice geometry, the samples show a large anisotropy in their electrical resistivity, which can be controlled by changing the thickness of the PbTiO3 layers. Therefore, along the ferroelectric direction, SrRuO3 layers can act as dielectric, rather than metallic, elements. We show that, by reducing the concentration of PbTiO3, an increasingly important effect of polarization asymmetry due to compositional inversion symmetry breaking occurs. The results are significant as they represent a new class of ferroelectric superlattices, with a rich and complex phase diagram. By expanding our set of materials we are able to introduce new behaviors that can only occur when one of the materials is not a perovskite titanate. Here, compositional inversion symmetry breaking in bicolor superlattices, due to the combined variation of A and B site ions within the superlattice, is demonstrated using a combination of experimental measurements and first principles density functional theory.
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Affiliation(s)
- S J Callori
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
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