1
|
Yan J, Shi R, Wei J, Li Y, Qi R, Wu M, Li X, Feng B, Gao P, Shibata N, Ikuhara Y. Nanoscale Localized Phonons at Al 2O 3 Grain Boundaries. NANO LETTERS 2024; 24:3323-3330. [PMID: 38466652 DOI: 10.1021/acs.nanolett.3c04149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Nanoscale defects like grain boundaries (GBs) would introduce local phonon modes and affect the bulk materials' thermal, electrical, optical, and mechanical properties. It is highly desirable to correlate the phonon modes and atomic arrangements for individual defects to precisely understand the structure-property relation. Here we investigated the localized phonon modes of Al2O3 GBs by combination of the vibrational electron energy loss spectroscopy (EELS) in scanning transmission electron microscope and density functional perturbation theory (DFPT). The differences between GB and bulk obtained from the vibrational EELS show that the GB exhibited more active vibration at the energy range of <50 meV and >80 meV, and further DFPT results proved the wide distribution of bond lengths at GB are the main factor for the emergence of local phonon modes. This research provides insights into the phonon-defect relation and would be of importance in the design and application of polycrystalline materials.
Collapse
Affiliation(s)
- Jingyuan Yan
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
| | - Ruochen Shi
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jiake Wei
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yuehui Li
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Ruishi Qi
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Peking University, Beijing 100871, China
- Department of Physics, University of California at Berkeley, Berkeley 94720, California, United States
| | - Mei Wu
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Xiaomei Li
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- School of Integrated Circuits, East China Normal University, Shanghai 200241, China
| | - Bin Feng
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Peng Gao
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
- International Center for Quantum Materials, Peking University, Beijing 100871, China
- Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China
| | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656, Japan
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan
| |
Collapse
|
2
|
Miao W, Zhen W, Tan C, Wang J, Nie Y, Wang H, Wang L, Niu Q, Tian M. Nonreciprocal Antisymmetric Magnetoresistance and Unconventional Hall Effect in a Two-Dimensional Ferromagnet. ACS NANO 2023; 17:25449-25458. [PMID: 38051216 DOI: 10.1021/acsnano.3c08954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Two-dimensional (2D) ferromagnets with high Curie temperatures provide a rich platform for exploring the exotic phenomena of 2D magnetism and the potential of spintronic devices. As a prototypical 2D ferromagnet, Fe5-xGeTe2 has recently been reported to possess a high Curie temperature with Tc ∼ 310 K, making it a promising candidate for advancing 2D nanoelectromechanical systems. However, due to its intricate magnetic ground state and magnetic domains, a thorough study of the transport behavior related to its lattice and domain structures is still lacking. Here, we report a nonreciprocal antisymmetric magnetoresistance in Fe5-xGeTe2 nanoflakes observed under an external magnetic field between 85-120 K. Through a detailed examination of its temperature, field orientation, and sample thickness dependence, we trace its origin to an additional electric field induced by the domain structure. This differs from the previously reported antisymmetric magnetoresistance due to thickness inhomogeneity. Notably, at lower temperatures, we observed an unconventional Hall effect (UHE), which can be attributed to the Dzyaloshinskii-Moriya interaction (DMI) resulting from the non-coplanar magnetic moment structure. The pronounced influence of sample thickness on magneto-transport properties underscores the competition between magnetic anisotropy and DMI in Fe5-xGeTe2 flakes with varying thicknesses. Our findings provide a deeper understanding of the magneto-transport behavior of the exotic magnetic structure in 2D ferromagnetic materials, which may benefit future spintronic device applications.
Collapse
Affiliation(s)
- Weiting Miao
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, Anhui, China
| | - Weili Zhen
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Cheng Tan
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Jie Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Yong Nie
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Hengning Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Lan Wang
- Lab of Low Dimensional Magnetism and Spintronic Devices, School of Physics, Hefei University of Technology, Hefei 230009, Anhui, China
| | - Qun Niu
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Mingliang Tian
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, Anhui, China
- School of Physics and Optoelectronic Engineering, Anhui University, Hefei 230601, Anhui, China
| |
Collapse
|
3
|
Zou Q, Oli BD, Zhang H, Benigno J, Li X, Li L. Deciphering Alloy Composition in Superconducting Single-Layer FeSe 1-xS x on SrTiO 3(001) Substrates by Machine Learning of STM/S Data. ACS APPLIED MATERIALS & INTERFACES 2023; 15:22644-22650. [PMID: 37125966 PMCID: PMC10176460 DOI: 10.1021/acsami.2c23324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Scanning tunneling microscopy (STM) is a powerful technique for imaging atomic structure and inferring information on local elemental composition, chemical bonding, and electronic excitations. However, a plain visual analysis of STM images can be challenging for such determination in multicomponent alloys, particularly beyond the diluted limit due to chemical disorder and electronic inhomogeneity. One viable solution is to use machine learning to analyze STM data and identify hidden patterns and correlations. Here, we apply this approach to determine the Se/S concentration in superconducting single-layer FeSe1-xSx alloys epitaxially grown on SrTiO3(001) substrates via molecular beam epitaxy. First, the K-means clustering method is applied to identify defect-related dI/dV tunneling spectra taken by current imaging tunneling spectroscopy. Then, the Se/S ratio is calculated by analyzing the remaining spectra based on the singular value decomposition method. Such analysis provides an efficient and reliable determination of alloy composition and further reveals the correlations of nanoscale chemical inhomogeneity to superconductivity in single-layer iron chalcogenide films.
Collapse
Affiliation(s)
- Qiang Zou
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Basu Dev Oli
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Huimin Zhang
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Joseph Benigno
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Xin Li
- Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Lian Li
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| |
Collapse
|
4
|
Xi M, Chen F, Gong C, Tian S, Yin Q, Qian T, Lei H. Relationship between Antisite Defects, Magnetism, and Band Topology in MnSb 2Te 4 Crystals with TC ≈ 40 K. J Phys Chem Lett 2022; 13:10897-10904. [PMID: 36394448 DOI: 10.1021/acs.jpclett.2c02775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
MnSb2Te4 has attracted extensive attention because of its rich and adjustable magnetic properties. Here, using a modified crystal growth method, ferrimagnetic MnSb2Te4 crystals with enhanced Curie temperature (TC) of about 40 K with dominant hole-type carriers and intrinsic anomalous Hall effect is obtained. Time- and angle-resolved photoemission spectroscopy reveals that surface states are absent in both antiferromagnetic and ferrimagnetic MnSb2Te4, implying that they have topologically trivial electronic structures. We propose that the enhancement of ferrimagnetism mainly originates from the increase of intralayer magnetic coupling caused by the decrease of Sb content at Mn sites when the decrease of Mn concentration at Sb sites would prefer the nontrival band topology. Moreover, it is known that the initial saturation moment (Mis) is sensitive to the concentrations of Mn/Sb antisite defects; thus, the Mis could be a valuable parameter to evaluate the magnetic and topological properties of MnX2nTe3n+1 (X = Bi, Sb) families.
Collapse
Affiliation(s)
- Ming Xi
- Laboratory for Neutron Scattering, and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Famin Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Science, Beijing 10049, China
| | - Chunsheng Gong
- Laboratory for Neutron Scattering, and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Shangjie Tian
- Laboratory for Neutron Scattering, and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Qiangwei Yin
- Laboratory for Neutron Scattering, and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| | - Tian Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Science, Beijing 10049, China
| | - Hechang Lei
- Laboratory for Neutron Scattering, and Beijing Key Laboratory of Optoelectronic Functional Materials MicroNano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
| |
Collapse
|
5
|
Yang H, Konečná A, Xu X, Cheong SW, Batson PE, García de Abajo FJ, Garfunkel E. Simultaneous Imaging of Dopants and Free Charge Carriers by Monochromated EELS. ACS NANO 2022; 16:18795-18805. [PMID: 36317944 DOI: 10.1021/acsnano.2c07540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Doping inhomogeneities in solids are not uncommon, but their microscopic observation and understanding are limited due to the lack of bulk-sensitive experimental techniques with high enough spatial and spectral resolution. Here, we demonstrate nanoscale imaging of both dopants and free charge carriers in La-doped BaSnO3 (BLSO) using high-resolution electron energy-loss spectroscopy (EELS). By analyzing high- and low-energy excitations in EELS, we reveal chemical and electronic inhomogeneities within a single BLSO nanocrystal. The inhomogeneous doping leads to distinctive localized infrared surface plasmons, including a previously unobserved plasmon mode that is highly confined between high- and low-doping regions. We further quantify the carrier density, effective mass, and dopant activation percentage by EELS and transport measurements on the bulk single crystals of BLSO. These results not only represent a practical approach for studying heterogeneities in solids and understanding structure-property relationships at the nanoscale, but also demonstrate the possibility of infrared plasmon tuning by leveraging nanoscale doping texture.
Collapse
Affiliation(s)
- Hongbin Yang
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey08854, United States
| | - Andrea Konečná
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860Castelldefels, Barcelona, Spain
- Central European Institute of Technology, Brno University of Technology, 61200Brno, Czech Republic
| | - Xianghan Xu
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey08854, United States
| | - Sang-Wook Cheong
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey08854, United States
| | - Philip E Batson
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey08854, United States
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860Castelldefels, Barcelona, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010Barcelona, Spain
| | - Eric Garfunkel
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey08854, United States
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey08854, United States
| |
Collapse
|