1
|
Lyu D, Shoup JE, Huang D, García-Barriocanal J, Jia Q, Echtenkamp W, Rojas GA, Yu G, Zink BR, Wang X, Gopman DB, Wang JP. Sputtered L1 0-FePd and its Synthetic Antiferromagnet on Si/SiO 2 Wafers for Scalable Spintronics. Adv Funct Mater 2023; 23:10.1002/adfm.202214201. [PMID: 37200959 PMCID: PMC10190167 DOI: 10.1002/adfm.202214201] [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: 12/05/2022] [Indexed: 05/20/2023]
Abstract
As a promising alternative to the mainstream CoFeB/MgO system with interfacial perpendicular magnetic anisotropy (PMA), L10-FePd and its synthetic antiferromagnet (SAF) structure with large crystalline PMA can support spintronic devices with sufficient thermal stability at sub-5 nm sizes. However, the compatibility requirement of preparing L10-FePd thin films on Si/SiO2 wafers is still unmet. In this paper, we prepare high-quality L10-FePd and its SAF on Si/SiO2 wafers by coating the amorphous SiO2 surface with an MgO(001) seed layer. The prepared L10-FePd single layer and SAF stack are highly (001)-textured, showing strong PMA, low damping, and sizeable interlayer exchange coupling, respectively. Systematic characterizations, including advanced X-ray diffraction measurement and atomic resolution-scanning transmission electron microscopy, are conducted to explain the outstanding performance of L10-FePd layers. A fully-epitaxial growth that starts from MgO seed layer, induces the (001) texture of L10-FePd, and extends through the SAF spacer is observed. This study makes the vision of scalable spintronics more practical.
Collapse
Affiliation(s)
- Deyuan Lyu
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jenae E Shoup
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Dingbin Huang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Qi Jia
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - William Echtenkamp
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Geoffrey A Rojas
- Characterization Facility, University of Minnesota, Minneapolis, MN 55455, USA
| | - Guichuan Yu
- Characterization Facility, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brandon R Zink
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Xiaojia Wang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel B Gopman
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| |
Collapse
|
2
|
Kim H, Van P, Jung H, Yang J, Jo Y, Yoo J, Park AM, Jeong J, Kim K. Deposition of Crystalline GdIG Samples Using Metal Organic Decomposition Method. Magnetochemistry 2022; 8:28. [DOI: 10.3390/magnetochemistry8030028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Fabrication of high quality ferrimagnetic insulators is an essential step for ultrafast magnonics, which utilizes antiferromagnetic exchange of the ferrimagnetic materials. In this work, we deposit high-quality GdIG thin films on a (111)-oriented GGG substrate using the Metal Organic Decomposition (MOD) method, a simple and high throughput method for depositing thin film materials. We postannealed samples at various temperatures and examined the effect on structural properties such as crystallinity and surface morphology. We found a transition in the growth mode that radically changes the morphology of the film as a function of annealing temperature and obtained an optimal annealing temperature for a uniform thin film with high crystallinity. Optimized GdIG has a high potential for spin wave applications with a low damping parameter in the order of 10−3, which persists down to cryogenic temperatures.
Collapse
|
3
|
Joo S, Alemayehu RS, Choi JG, Park BG, Choi GM. Magnetic Anisotropy and Damping Constant of Ferrimagnetic GdCo Alloy near Compensation Point. Materials (Basel) 2021; 14:2604. [PMID: 34067665 DOI: 10.3390/ma14102604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/11/2021] [Accepted: 05/14/2021] [Indexed: 11/16/2022]
Abstract
Metallic ferrimagnets with rare earth-transition metal alloys can provide novel properties that cannot be obtained using conventional ferromagnets. Recently, the compensation point of ferrimagnets, where the net magnetization or net angular momentum vanishes, has been considered a key aspect for memory device applications. For such applications, the magnetic anisotropy energy and damping constant are crucial. In this study, we investigate the magnetic anisotropy and damping constant of a GdCo alloy, with a Gd concentration of 12–27%. By analyzing the equilibrium tilting of magnetization as a function of the applied magnetic field, we estimate the uniaxial anisotropy to be 1–3 × 104 J m−3. By analyzing the transient dynamics of magnetization as a function of time, we estimate the damping constant to be 0.08–0.22.
Collapse
|
4
|
Miwa S, Iihama S, Nomoto T, Tomita T, Higo T, Ikhlas M, Sakamoto S, Otani Y, Mizukami S, Arita R, Nakatsuji S. Giant Effective Damping of Octupole Oscillation in an Antiferromagnetic Weyl Semimetal. Small Science 2021. [DOI: 10.1002/smsc.202000062] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Shinji Miwa
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
- Trans-scale Quantum Science Institute The University of Tokyo Bunkyo Tokyo 113-0033 Japan
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
| | - Satoshi Iihama
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- Frontier Research Institute for Interdisciplinary Sciences (FRIS) Tohoku University Sendai Miyagi 980-8578 Japan
- Advanced Institute for Materials Research (AIMR) Tohoku University Sendai Miyagi 980-8577 Japan
- Center for Spintronics Research Network (CSRN) Tohoku University Sendai Miyagi 980-8577 Japan
| | - Takuya Nomoto
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- Department of Applied Physics The University of Tokyo Tokyo 113-8656 Japan
| | - Takahiro Tomita
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
| | - Tomoya Higo
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- Department of Physics The University of Tokyo Tokyo 113-0033 Japan
| | - Muhammad Ikhlas
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
| | - Shoya Sakamoto
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
| | - YoshiChika Otani
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
- Trans-scale Quantum Science Institute The University of Tokyo Bunkyo Tokyo 113-0033 Japan
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- RIKEN, Center for Emergent Matter Science (CEMS) Wako Saitama 351-0198 Japan
| | - Shigemi Mizukami
- Advanced Institute for Materials Research (AIMR) Tohoku University Sendai Miyagi 980-8577 Japan
- Center for Spintronics Research Network (CSRN) Tohoku University Sendai Miyagi 980-8577 Japan
- Center for Science and Innovation in Spintronics (CSIS) Tohoku University Sendai Miyagi 980-8577 Japan
| | - Ryotaro Arita
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- Department of Applied Physics The University of Tokyo Tokyo 113-8656 Japan
- RIKEN, Center for Emergent Matter Science (CEMS) Wako Saitama 351-0198 Japan
| | - Satoru Nakatsuji
- The Institute for Solid State Physics The University of Tokyo Kashiwa Chiba 277-8581 Japan
- Trans-scale Quantum Science Institute The University of Tokyo Bunkyo Tokyo 113-0033 Japan
- CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan
- Department of Physics The University of Tokyo Tokyo 113-0033 Japan
| |
Collapse
|
5
|
Shao Q, Li P, Liu L, Yang H, Fukami S, Razavi A, Wu H, Wang K, Freimuth F, Mokrousov Y, Stiles MD, Emori S, Hoffmann A, Åkerman J, Roy K, Wang JP, Yang SH, Garello K, Zhang W. Roadmap of spin-orbit torques. IEEE Trans Magn 2021; 57:10.48550/arXiv.2104.11459. [PMID: 37057056 PMCID: PMC10091395 DOI: 10.48550/arxiv.2104.11459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Spin-orbit torque (SOT) is an emerging technology that enables the efficient manipulation of spintronic devices. The initial processes of interest in SOTs involved electric fields, spin-orbit coupling, conduction electron spins and magnetization. More recently interest has grown to include a variety of other processes that include phonons, magnons, or heat. Over the past decade, many materials have been explored to achieve a larger SOT efficiency. Recently, holistic design to maximize the performance of SOT devices has extended material research from a nonmagnetic layer to a magnetic layer. The rapid development of SOT has spurred a variety of SOT-based applications. In this Roadmap paper, we first review the theories of SOTs by introducing the various mechanisms thought to generate or control SOTs, such as the spin Hall effect, the Rashba-Edelstein effect, the orbital Hall effect, thermal gradients, magnons, and strain effects. Then, we discuss the materials that enable these effects, including metals, metallic alloys, topological insulators, two-dimensional materials, and complex oxides. We also discuss the important roles in SOT devices of different types of magnetic layers, such as magnetic insulators, antiferromagnets, and ferrimagnets. Afterward, we discuss device applications utilizing SOTs. We discuss and compare three-terminal and two-terminal SOT-magnetoresistive random-access memories (MRAMs); we mention various schemes to eliminate the need for an external field. We provide technological application considerations for SOT-MRAM and give perspectives on SOT-based neuromorphic devices and circuits. In addition to SOT-MRAM, we present SOT-based spintronic terahertz generators, nano-oscillators, and domain wall and skyrmion racetrack memories. This paper aims to achieve a comprehensive review of SOT theory, materials, and applications, guiding future SOT development in both the academic and industrial sectors.
Collapse
Affiliation(s)
- Qiming Shao
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology
| | - Peng Li
- Department of Electrical and Computer Engineering, Auburn University
| | - Luqiao Liu
- Electrical Engineering and Computer Science, Massachusetts Institute of Technology
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore
| | - Shunsuke Fukami
- Research Institute of Electrical Communication, Tohoku University
| | - Armin Razavi
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | - Hao Wu
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | - Kang Wang
- Department of Electrical and Computer Engineering, University of California, Los Angeles
| | | | | | - Mark D Stiles
- Alternative Computing Group, National Institute of Standards and Technology
| | | | - Axel Hoffmann
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign
| | | | - Kaushik Roy
- Department of Electrical and Computer Engineering, Purdue University
| | - Jian-Ping Wang
- Electrical and Computer Engineering Department, University of Minnesota
| | | | - Kevin Garello
- IMEC, Leuven, Belgium; CEA-Spintec, Grenoble, France
| | - Wei Zhang
- Physics Department, Oakland University
| |
Collapse
|
6
|
Caretta L, Oh SH, Fakhrul T, Lee DK, Lee BH, Kim SK, Ross CA, Lee KJ, Beach GSD. Relativistic kinematics of a magnetic soliton. Science 2020; 370:1438-1442. [PMID: 33335059 DOI: 10.1126/science.aba5555] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 05/19/2020] [Accepted: 11/13/2020] [Indexed: 11/02/2022]
Abstract
A tenet of special relativity is that no particle can exceed the speed of light. In certain magnetic materials, the maximum magnon group velocity serves as an analogous relativistic limit for the speed of magnetic solitons. Here, we drive domain walls to this limit in a low-dissipation magnetic insulator using pure spin currents from the spin Hall effect. We achieve record current-driven velocities in excess of 4300 meters per second-within ~10% of the relativistic limit-and we observe key signatures of relativistic motion associated with Lorentz contraction, which leads to velocity saturation. The experimental results are well explained through analytical and atomistic modeling. These observations provide critical insight into the fundamental limits of the dynamics of magnetic solitons and establish a readily accessible experimental framework to study relativistic solitonic physics.
Collapse
Affiliation(s)
- Lucas Caretta
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Se-Hyeok Oh
- Department of Nano-Semiconductor and Engineering, Korea University, Seoul 02841, Korea
| | - Takian Fakhrul
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Dong-Kyu Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
| | - Byung Hun Lee
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Se Kwon Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Kyung-Jin Lee
- Department of Nano-Semiconductor and Engineering, Korea University, Seoul 02841, Korea.,Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea.,Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
| |
Collapse
|
7
|
Haltz E, Sampaio J, Krishnia S, Berges L, Weil R, Mougin A. Measurement of the tilt of a moving domain wall shows precession-free dynamics in compensated ferrimagnets. Sci Rep 2020; 10:16292. [PMID: 33004853 DOI: 10.1038/s41598-020-73049-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/03/2020] [Indexed: 11/15/2022] Open
Abstract
One fundamental obstacle to efficient ferromagnetic spintronics is magnetic precession, which intrinsically limits the dynamics of magnetic textures. We experimentally demonstrate that this precession vanishes when the net angular momentum is compensated in domain walls driven by spin–orbit torque in a ferrimagnetic GdFeCo/Pt track. We use transverse in-plane fields to provide a robust and parameter-free measurement of the domain wall internal magnetisation angle, demonstrating that, at the angular compensation, the DW tilt is zero, and thus the magnetic precession that caused it is suppressed. Our results highlight the mechanism of faster and more efficient dynamics in materials with multiple spin lattices and vanishing net angular momentum, promising for high-speed, low-power spintronic applications.
Collapse
|
8
|
Kim C, Lee S, Kim HG, Park JH, Moon KW, Park JY, Yuk JM, Lee KJ, Park BG, Kim SK, Kim KJ, Hwang C. Distinct handedness of spin wave across the compensation temperatures of ferrimagnets. Nat Mater 2020; 19:980-985. [PMID: 32601483 DOI: 10.1038/s41563-020-0722-8] [Citation(s) in RCA: 2] [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: 11/07/2019] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
Antiferromagnetic spin waves have been predicted to offer substantial functionalities for magnonic applications due to the existence of two distinct polarizations, the right-handed and left-handed modes, as well as their ultrafast dynamics. However, experimental investigations have been hampered by the field-immunity of antiferromagnets. Ferrimagnets have been shown to be an alternative platform to study antiferromagnetic spin dynamics. Here we investigate thermally excited spin waves in ferrimagnets across the magnetization compensation and angular momentum compensation temperatures using Brillouin light scattering. Our results show that right-handed and left-handed modes intersect at the angular momentum compensation temperature where pure antiferromagnetic spin waves are expected. A field-induced shift of the mode-crossing point from the angular momentum compensation temperature and the gyromagnetic reversal reveal hitherto unrecognized properties of ferrimagnetic dynamics. We also provide a theoretical understanding of our experimental results. Our work demonstrates important aspects of the physics of ferrimagnetic spin waves and opens up the attractive possibility of ferrimagnet-based magnonic devices.
Collapse
Affiliation(s)
- Changsoo Kim
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
- Department of Physics, KAIST, Daejeon, Republic of Korea
| | - Soogil Lee
- Department of Physics, KAIST, Daejeon, Republic of Korea
- Department of Materials Science and Engineering and KI for Nanocentury, KAIST, Daejeon, Republic of Korea
| | - Hyun-Gyu Kim
- Department of Physics, KAIST, Daejeon, Republic of Korea
| | - Ji-Ho Park
- Department of Physics, KAIST, Daejeon, Republic of Korea
| | - Kyung-Woong Moon
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Jae Yeol Park
- Department of Materials Science and Engineering and KI for Nanocentury, KAIST, Daejeon, Republic of Korea
| | - Jong Min Yuk
- Department of Materials Science and Engineering and KI for Nanocentury, KAIST, Daejeon, Republic of Korea
| | - Kyung-Jin Lee
- Department of Nano-Semiconductor and Engineering, Korea University, Seoul, Republic of Korea
- Department of Materials Science & Engineering, Korea University, Seoul, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Byong-Guk Park
- Department of Materials Science and Engineering and KI for Nanocentury, KAIST, Daejeon, Republic of Korea
| | - Se Kwon Kim
- Department of Physics, KAIST, Daejeon, Republic of Korea.
- Department of Physics and Astronomy, University of Missouri, Columbia, MO, USA.
| | - Kab-Jin Kim
- Department of Physics, KAIST, Daejeon, Republic of Korea.
| | - Chanyong Hwang
- Quantum Spin Team, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea.
| |
Collapse
|
9
|
Martínez E, Raposo V, Alejos Ó. Novel interpretation of recent experiments on the dynamics of domain walls along ferrimagnetic strips. J Phys Condens Matter 2020; 32:465803. [PMID: 32693394 DOI: 10.1088/1361-648x/aba7eb] [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
Domain wall motion along ferrimagnets is evaluated using micromagnetic simulations and a collective-coordinates model, both considering two sublattices with independent parameters. Analytical expressions are derived for strips on top of either a heavy metal or a substrate with negligible interfacial Dzyaloshinskii-Moriya interaction. The work focuses its findings in this latter case, with a field-driven domain wall motion depicting precessional dynamics which become rigid at the angular momentum compensation temperature, and a current-driven dynamics presenting more complex behavior, depending on the polarization factors for each sublattice. Importantly, our analyses provide also novel interpretation of recent evidence on current-driven domain wall motion, where walls move either along or against the current depending on temperature. Besides, our approach is able to substantiate the large non-adiabatic effective parameters found for these systems.
Collapse
Affiliation(s)
- Eduardo Martínez
- Dpto. Física Aplicada, Universidad de Salamanca, 37008 Salamanca, Spain
| | | | | |
Collapse
|
10
|
Shim J, Kim SJ, Kim SK, Lee KJ. Enhanced Magnon-Photon Coupling at the Angular Momentum Compensation Point of Ferrimagnets. Phys Rev Lett 2020; 125:027205. [PMID: 32701310 DOI: 10.1103/physrevlett.125.027205] [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] [Received: 03/06/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
We theoretically show that the coupling between magnons in an antiferromagnetically coupled ferrimagnet and microwave photons in a cavity is largely enhanced at the angular momentum compensation point (T_{A}) when T_{A} is distinct from the magnetization compensation point. The origin of the enhanced magnon-photon coupling at T_{A} is identified as the antiferromagnetic spin dynamics combined with a finite magnetization. Moreover, we show that strong magnon-photon coupling can be achieved at high excitation frequency in a ferrimagnet, which is challenging to achieve for a ferromagnet due to low magnon frequency and for an antiferromagnet due to weak magnon-photon coupling. Our results will invigorate research on magnon-photon coupling by proposing ferrimagnets as a versatile platform that offers advantages of both ferromagnets and antiferromagnets.
Collapse
Affiliation(s)
- Jaechul Shim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- Semiconductor R&D Center, Samsung Electronics Co. Ltd., Hwaseong, Gyeonggi 18448, Korea
| | - Seok-Jong Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Se Kwon Kim
- Department of Physics, KAIST, Daejeon 34141, Korea
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| |
Collapse
|