1
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Mishra SS, Lourembam J, Lin DJX, Singh R. Active ballistic orbital transport in Ni/Pt heterostructure. Nat Commun 2024; 15:4568. [PMID: 38811558 PMCID: PMC11137139 DOI: 10.1038/s41467-024-48891-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 05/15/2024] [Indexed: 05/31/2024] Open
Abstract
Orbital current, defined as the orbital character of Bloch states in solids, can travel with larger coherence length through a broader range of materials than its spin counterpart, facilitating a robust, higher density and energy efficient information transmission. Hence, active control of orbital transport plays a pivotal role in the progress of the evolving field of quantum information technology. Unlike spin angular momentum, orbital angular momentum couples to phonon angular momentum efficiently via orbital-crystal momentum (L-k) coupling, allowing us to control orbital transport through crystal field potential mediated angular momentum transfer. Here, leveraging the orbital dependant efficient L-k coupling, we have experimentally demonstrated the active control of orbital current velocity in Ni/Pt heterostructure. We observe terahertz emission from Ni/Pt heterostructure via long-range ballistic orbital transport, as evidenced by the delay, and chirping in the emitted THz pulse correlating with increased Pt thickness. Additionally, we also have identified a critical energy density required to overcome collisions in orbital transport, enabling a swifter flow of orbital current. Femtosecond light driven active control of the ballistic orbital transport lays the foundation for the development of dynamic optorbitronics for transmitting information over extended distance.
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Affiliation(s)
- Sobhan Subhra Mishra
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore
| | - James Lourembam
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore, 138364, Singapore
| | - Dennis Jing Xiong Lin
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore, 138364, Singapore
| | - Ranjan Singh
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, Singapore, 639798, Singapore.
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2
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Huang L, Liao L, Qiu H, Chen X, Bai H, Han L, Zhou Y, Su Y, Zhou Z, Pan F, Jin B, Song C. Antiferromagnetic magnonic charge current generation via ultrafast optical excitation. Nat Commun 2024; 15:4270. [PMID: 38769299 PMCID: PMC11106255 DOI: 10.1038/s41467-024-48391-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 04/30/2024] [Indexed: 05/22/2024] Open
Abstract
Néel spin-orbit torque allows a charge current pulse to efficiently manipulate the Néel vector in antiferromagnets, which offers a unique opportunity for ultrahigh density information storage with high speed. However, the reciprocal process of Néel spin-orbit torque, the generation of ultrafast charge current in antiferromagnets has not been demonstrated. Here, we show the experimental observation of charge current generation in antiferromagnetic metallic Mn2Au thin films using ultrafast optical excitation. The ultrafast laser pulse excites antiferromagnetic magnons, resulting in instantaneous non-equilibrium spin polarization at the antiferromagnetic spin sublattices with broken spatial symmetry. Then the charge current is generated directly via spin-orbit fields at the two sublattices, which is termed as the reciprocal phenomenon of Néel spin-orbit torque, and the associated THz emission can be detected at room temperature. Besides the fundamental significance on the Onsager reciprocity, the observed magnonic charge current generation in antiferromagnet would advance the development of antiferromagnetic THz emitter.
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Affiliation(s)
- Lin Huang
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Liyang Liao
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - Hongsong Qiu
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Xianzhe Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Hua Bai
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Lei Han
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Yongjian Zhou
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Yichen Su
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Zhiyuan Zhou
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Feng Pan
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China
| | - Biaobing Jin
- Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing, China.
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, China.
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3
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Liu L, Ren Y, Robert W, Wang L, Wang X, Yang C. Terahertz wave radiation simulation in the Fe thin film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:305902. [PMID: 38653257 DOI: 10.1088/1361-648x/ad4222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 04/23/2024] [Indexed: 04/25/2024]
Abstract
Femtosecond laser (FL) induced terahertz (THz) source is a new type of THz source based on injecting FL beams into ferromagnetic thin films by nonlinear effects to generate THz wave. It has a wider bandwidth compared to the traditional THz source, which provides higher flexibility and tunability in the application. In this paper, the three-temperature model and the stochastic Landau Lifshitz Gilbert equation at the atomic level are applied to simulate THz wave generation in Fe thin film induced by FL. Simulation results show that under a FL irradiance of 2 J m-2, the maximum demagnetization of the Fe thin film reaches 8.7%. The electromagnetic waves generated completely cover the THz band (0.1-10 THz), which fully satisfied the application requirements of the THz technology, verifying the feasibility of FL inducing the Fe thin film as a THz source. However, when the Fe thin film is overheated, it will be difficult for FL to excite valuable THz waves. Therefore, additional cooling devices are needed to keep the THz source in a workable temperature state, or to use ferromagnetic materials with magnetic moments that can quickly recover to saturation.
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Affiliation(s)
- Liwang Liu
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China
| | - Yifan Ren
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
- Science Island Branch, Graduate School of University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Wieser Robert
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China
| | - Lu Wang
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China
| | - Xuan Wang
- Department of Physics, School of Science, Lanzhou University of Technology, Lanzhou 730050, People's Republic of China
| | - Cuihong Yang
- School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China
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4
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Nwaji N, Gwak J, Nguyen MC, Nguyen HQ, Kang H, Choi Y, Kim Y, Chen H, Lee J. Emerging potentials of Fe-based nanomaterials for chiral sensing and imaging. Med Res Rev 2024; 44:897-918. [PMID: 38084636 DOI: 10.1002/med.22003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 04/11/2023] [Accepted: 11/26/2023] [Indexed: 04/06/2024]
Abstract
Fe-based nanostructures have possessed promising properties that make it suitable for chiral sensing and imaging applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photostability, tunable fluorescence, and water solubility. This review summarizes the recent research progress in the field of Fe-based nanostructures and places special emphases on their applications in chiral sensing and imaging. The synthetic strategies to prepare the targeted Fe-based structures were also introduced. The chiral sensing and imaging applications of the nanostructures are discussed in details.
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Affiliation(s)
- Njemuwa Nwaji
- Institute of Materials Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Juyong Gwak
- Department of Chemistry, Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - My-Chi Nguyen
- Institute of Materials Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Huu-Quang Nguyen
- Institute of Materials Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Hyojin Kang
- Department of Chemistry, Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Youngeun Choi
- Department of Chemistry, Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Youngmi Kim
- Department of Chemistry, Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
| | - Hongxia Chen
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, PR China
| | - Jaebeom Lee
- Institute of Materials Chemistry, Chungnam National University, Daejeon, Republic of Korea
- Department of Chemistry, Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon, Republic of Korea
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5
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Song Y, Ji Z, Zhang Y, Song Y, Li Z, Zhang J, Zhang J, Jiang Z, Liu Y, Jin Q, Zhang Z. High Efficiency and Flexible Modulation of Spintronic Terahertz Emitters in Synthetic Antiferromagnets. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37883114 DOI: 10.1021/acsami.3c11533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Spintronic terahertz (THz) emitters based on synthetic antiferromagnets (SAFs) of FM1/Ru/FM2 (FM: ferromagnet) have shown great potential for achieving coherent superposition and significant THz power enhancement due to antiparallel magnetization alignment. However, key issues regarding the effects of interlayer exchange coupling and net magnetization on THz emissions remain unclear, which will inevitably hinder the performance improvement and practical application of THz devices. In this work, we have investigated the femtosecond laser-induced THz emission in Pt (3)/CoFe (3)/Ru (tRu = 0-3.5)/CoFe (tCoFe = 1.5-10)/Pt (3) (in units of nm) films with compensated and uncompensated magnetic moments. Antiferromagnetic (AF) coupling occurs in the Ru thickness ranges of 0.2-1.1 and 1.9-2.3 nm, with the first peak (tRu = 0.4 nm) of the AF coupling field (Hex) significantly higher than that of the second peak (2.0 nm). Rather high THz amplitude is found for the samples with strong AF coupling. Nevertheless, despite the same remanence ratio of zero, the THz amplitude for the symmetric SAF films declines significantly as the tRu decreases from 0.8 to 0.4 nm, which is mainly ascribed to the noncolinear magnetization vectors due to the increased biquadratic coupling term. Specifically, we demonstrate that an asymmetric SAF structure with a dominant FM layer is more favored than the completely compensated one, which could generate significantly enhanced THz electric field with well-controlled polarity and intensity. In addition, as the temperature decreases, the THz emission intensity increases for the SAF samples of tRu = 0.9 nm with negligible biquadratic coupling, which is contrary to the decreasing trend of the tRu = 0.4 nm sample and has been attributed to the greatly enhanced Hex.
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Affiliation(s)
- Yiwen Song
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Zhihao Ji
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Yu Zhang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Yuna Song
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Ziyang Li
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Jingying Zhang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Jiali Zhang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Zhiyao Jiang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Yaowen Liu
- School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Qingyuan Jin
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
| | - Zongzhi Zhang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Research Center and Key Laboratory of Micro and Nano Photonic Structures (MOE), School of Information Science and Technology, Fudan University, Shanghai 200433, China
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6
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Seifert TS, Go D, Hayashi H, Rouzegar R, Freimuth F, Ando K, Mokrousov Y, Kampfrath T. Time-domain observation of ballistic orbital-angular-momentum currents with giant relaxation length in tungsten. NATURE NANOTECHNOLOGY 2023; 18:1132-1138. [PMID: 37550573 PMCID: PMC10575790 DOI: 10.1038/s41565-023-01470-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 06/29/2023] [Indexed: 08/09/2023]
Abstract
The emerging field of orbitronics exploits the electron orbital momentum L. Compared to spin-polarized electrons, L may allow the transfer of magnetic information with considerably higher density over longer distances in more materials. However, direct experimental observation of L currents, their extended propagation lengths and their conversion into charge currents has remained challenging. Here, we optically trigger ultrafast angular-momentum transport in Ni|W|SiO2 thin-film stacks. The resulting terahertz charge-current bursts exhibit a marked delay and width that grow linearly with the W thickness. We consistently ascribe these observations to a ballistic L current from Ni through W with a giant decay length (~80 nm) and low velocity (~0.1 nm fs-1). At the W/SiO2 interface, the L flow is efficiently converted into a charge current by the inverse orbital Rashba-Edelstein effect, consistent with ab initio calculations. Our findings establish orbitronic materials with long-distance ballistic L transport as possible candidates for future ultrafast devices and an approach to discriminate Hall-like and Rashba-Edelstein-like conversion processes.
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Affiliation(s)
- Tom S Seifert
- Department of Physics, Freie Universität Berlin, Berlin, Germany.
- Department of Physical Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany.
| | - Dongwook Go
- Peter-Grünberg-Institut, Forschungszentrum Jülich, Jülich, Germany
- Institute of Physics, Johannes-Gutenberg-Universität Mainz, Mainz, Germany
| | - Hiroki Hayashi
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama, Japan
- Keio Institute of Pure and Applied Sciences, Keio University, Yokohama, Japan
| | - Reza Rouzegar
- Department of Physics, Freie Universität Berlin, Berlin, Germany
- Department of Physical Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
| | - Frank Freimuth
- Peter-Grünberg-Institut, Forschungszentrum Jülich, Jülich, Germany
- Keio Institute of Pure and Applied Sciences, Keio University, Yokohama, Japan
| | - Kazuya Ando
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama, Japan
- Keio Institute of Pure and Applied Sciences, Keio University, Yokohama, Japan
- Center for Spintronics Research Network, Keio University, Yokohama, Japan
| | - Yuriy Mokrousov
- Peter-Grünberg-Institut, Forschungszentrum Jülich, Jülich, Germany
- Institute of Physics, Johannes-Gutenberg-Universität Mainz, Mainz, Germany
| | - Tobias Kampfrath
- Department of Physics, Freie Universität Berlin, Berlin, Germany
- Department of Physical Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
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7
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Feng Z, Tan W, Jin Z, Chen YJ, Zhong Z, Zhang L, Sun S, Tang J, Jiang Y, Wu PH, Cheng J, Miao B, Ding H, Wang D, Zhu Y, Guo L, Shin S, Ma GH, Hou D, Huang SY. Anomalous Nernst Effect Induced Terahertz Emission in a Single Ferromagnetic Film. NANO LETTERS 2023; 23:8171-8179. [PMID: 37638840 DOI: 10.1021/acs.nanolett.3c02320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
Abstract
Despite its important role in understanding ultrafast spin dynamics and revealing novel spin/orbit effects, the mechanism of the terahertz (THz) emission from a single ferromagnetic nanofilm upon a femtosecond laser pump still remains elusive. Recent experiments have shown exotic symmetry, which is not expected from the routinely adopted mechanism of ultrafast demagnetization. Here, by developing a bidirectional pump-THz emission spectroscopy and associated symmetry analysis method, we set a benchmark for the experimental distinction of the THz emission induced by various mechanisms. Our results unambiguously unveil a new mechanism─anomalous Nernst effect (ANE) induced THz emission due to the ultrafast temperature gradient created by a femtosecond laser. Quantitative analysis shows that the THz emission exhibits interesting thickness dependence where different mechanisms dominate at different thickness ranges. Our work not only clarifies the origin of the ferromagnetic-based THz emission but also offers a fertile platform for investigating the ultrafast optomagnetism and THz spintronics.
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Affiliation(s)
- Zheng Feng
- Microsystem & Terahertz Research Center, CAEP, Chengdu 610200, P. R. China
| | - Wei Tan
- Microsystem & Terahertz Research Center, CAEP, Chengdu 610200, P. R. China
| | - Zuanming Jin
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - Yi-Jia Chen
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Zhangfeng Zhong
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Liang Zhang
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
- Department of Mechanical Engineering, National University of Singapore, 117516 Singapore
| | - Song Sun
- Microsystem & Terahertz Research Center, CAEP, Chengdu 610200, P. R. China
| | - Jin Tang
- School of Physics and Optoelectronics Engineering Science, Anhui University, Hefei 230601, P. R. China
| | - Yexing Jiang
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - Po-Hsun Wu
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Jun Cheng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Bingfeng Miao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Haifeng Ding
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, P. R. China
| | - Dacheng Wang
- Microsystem & Terahertz Research Center, CAEP, Chengdu 610200, P. R. China
| | - Yiming Zhu
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - Liang Guo
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Sunmi Shin
- Department of Mechanical Engineering, National University of Singapore, 117516 Singapore
| | - Guo-Hong Ma
- Department of Physics, Shanghai University, Shanghai 200444, P. R. China
| | - Dazhi Hou
- ICQD, Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, P. R. China
- Department of Physics, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Ssu-Yen Huang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
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8
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Jiang Y, Li Z, Li Z, Jin Z, Lu X, Xu Y, Peng Y, Zhu Y. Ultrafast light-driven magneto-optical nonlinearity in ferromagnetic heterostructures. OPTICS LETTERS 2023; 48:2054-2057. [PMID: 37058640 DOI: 10.1364/ol.485966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/19/2023] [Indexed: 06/19/2023]
Abstract
The dynamic control of magnetization by short laser pulses has recently attracted interest. The transient magnetization at the metallic magnetic interface has been investigated through second-harmonic generation and the time-resolved magneto-optical effect. However, the ultrafast light-driven magneto-optical nonlinearity in ferromagnetic heterostructures for terahertz (THz) radiation remains unclear. Here, we present THz generation from a metallic heterostructure, Pt/CoFeB/Ta, which is ascribed to an ∼6-8% contribution from the magnetization-induced optical rectification and an ∼94-92% contribution from both spin-to-charge current conversion and ultrafast demagnetization. Our results show that THz-emission spectroscopy is a powerful tool to study the picosecond-time-scale nonlinear magneto-optical effect in ferromagnetic heterostructures.
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9
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Mottamchetty V, Rani P, Brucas R, Rydberg A, Svedlindh P, Gupta R. Direct evidence of terahertz emission arising from anomalous Hall effect. Sci Rep 2023; 13:5988. [PMID: 37045934 PMCID: PMC10097872 DOI: 10.1038/s41598-023-33143-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/07/2023] [Indexed: 04/14/2023] Open
Abstract
A detailed understanding of the different mechanisms being responsible for terahertz (THz) emission in ferromagnetic (FM) materials will aid in designing efficient THz emitters. In this report, we present direct evidence of THz emission from single layer Co[Formula: see text]Fe[Formula: see text]B[Formula: see text] (CoFeB) FM thin films. The dominant mechanism being responsible for the THz emission is the anomalous Hall effect (AHE), which is an effect of a net backflow current in the FM layer created by the spin polarized current reflected at the interfaces of the FM layer. The THz emission from the AHE-based CoFeB emitter is optimized by varying its thickness, orientation, and pump fluence of the laser beam. Results from electrical transport measurements show that skew scattering of charge carriers is responsible for the THz emission in the CoFeB AHE-based THz emitter.
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Affiliation(s)
- Venkatesh Mottamchetty
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
| | - Parul Rani
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
| | - Rimantas Brucas
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
| | - Anders Rydberg
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
| | - Peter Svedlindh
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden.
| | - Rahul Gupta
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden.
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden.
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10
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Rongione E, Gueckstock O, Mattern M, Gomonay O, Meer H, Schmitt C, Ramos R, Kikkawa T, Mičica M, Saitoh E, Sinova J, Jaffrès H, Mangeney J, Goennenwein STB, Geprägs S, Kampfrath T, Kläui M, Bargheer M, Seifert TS, Dhillon S, Lebrun R. Emission of coherent THz magnons in an antiferromagnetic insulator triggered by ultrafast spin-phonon interactions. Nat Commun 2023; 14:1818. [PMID: 37002246 PMCID: PMC10066367 DOI: 10.1038/s41467-023-37509-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Antiferromagnetic materials have been proposed as new types of narrowband THz spintronic devices owing to their ultrafast spin dynamics. Manipulating coherently their spin dynamics, however, remains a key challenge that is envisioned to be accomplished by spin-orbit torques or direct optical excitations. Here, we demonstrate the combined generation of broadband THz (incoherent) magnons and narrowband (coherent) magnons at 1 THz in low damping thin films of NiO/Pt. We evidence, experimentally and through modeling, two excitation processes of spin dynamics in NiO: an off-resonant instantaneous optical spin torque in (111) oriented films and a strain-wave-induced THz torque induced by ultrafast Pt excitation in (001) oriented films. Both phenomena lead to the emission of a THz signal through the inverse spin Hall effect in the adjacent heavy metal layer. We unravel the characteristic timescales of the two excitation processes found to be < 50 fs and > 300 fs, respectively, and thus open new routes towards the development of fast opto-spintronic devices based on antiferromagnetic materials.
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Affiliation(s)
- E Rongione
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - O Gueckstock
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany
| | - M Mattern
- Institut für Physik und Astronomie, Universität Potsdam, D-14476, Potsdam, Germany
| | - O Gomonay
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - H Meer
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - C Schmitt
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - R Ramos
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, J-980-8577, Japan
- Centro Singular de Investigación en Química Bilóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - T Kikkawa
- Department of Applied Physics, The University of Tokyo, Tokyo, J-113-8656, Japan
| | - M Mičica
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - E Saitoh
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, J-980-8577, Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, J-113-8656, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, J-113-8656, Japan
| | - J Sinova
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
| | - H Jaffrès
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France
| | - J Mangeney
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - S T B Goennenwein
- Department of Physics, University of Konstanz, D-78457, Konstanz, Germany
| | - S Geprägs
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748, Garching, Germany
| | - T Kampfrath
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany
| | - M Kläui
- Institute of Physics, Johannes Gutenberg-University Mainz, D-55099, Mainz, Germany
- Graduate School of Excellence Materials Science in Mainz (MAINZ), Staudingerweg 9, D-55128, Mainz, Germany
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, N-7034, Trondheim, Norway
| | - M Bargheer
- Institut für Physik und Astronomie, Universität Potsdam, D-14476, Potsdam, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen Campus, BESSY II, Albert-Einstein-Strasse 15, D-12489, Berlin, Germany
| | - T S Seifert
- Institute of Physics, Freie Universität Berlin, D-14195, Berlin, Germany.
| | - S Dhillon
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - R Lebrun
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, F-91767, Palaiseau, France.
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11
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Dong J, You P, Tomasino A, Yurtsever A, Morandotti R. Single-shot ultrafast terahertz photography. Nat Commun 2023; 14:1704. [PMID: 36973242 PMCID: PMC10042990 DOI: 10.1038/s41467-023-37285-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 03/07/2023] [Indexed: 03/29/2023] Open
Abstract
Multidimensional imaging of transient events has proven pivotal in unveiling many fundamental mechanisms in physics, chemistry, and biology. In particular, real-time imaging modalities with ultrahigh temporal resolutions are required for capturing ultrashort events on picosecond timescales. Despite recent approaches witnessing a dramatic boost in high-speed photography, current single-shot ultrafast imaging schemes operate only at conventional optical wavelengths, being suitable solely within an optically-transparent framework. Here, leveraging on the unique penetration capability of terahertz radiation, we demonstrate a single-shot ultrafast terahertz photography system that can capture multiple frames of a complex ultrafast scene in non-transparent media with sub-picosecond temporal resolution. By multiplexing an optical probe beam in both the time and spatial-frequency domains, we encode the terahertz-captured three-dimensional dynamics into distinct spatial-frequency regions of a superimposed optical image, which is then computationally decoded and reconstructed. Our approach opens up the investigation of non-repeatable or destructive events that occur in optically-opaque scenarios.
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Affiliation(s)
- Junliang Dong
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, Varennes, QC, J3X 1P7, Canada.
| | - Pei You
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, Varennes, QC, J3X 1P7, Canada
| | - Alessandro Tomasino
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, Varennes, QC, J3X 1P7, Canada
| | - Aycan Yurtsever
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, Varennes, QC, J3X 1P7, Canada
| | - Roberto Morandotti
- Institut national de la recherche scientifique, Centre Énergie Matériaux Télécommunications, Varennes, QC, J3X 1P7, Canada.
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12
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Li Z, Jiang Y, Jin Z, Li Z, Lu X, Ye Z, Pang JY, Xu Y, Peng Y. Terahertz Emission Spectroscopy of Ultrafast Coupled Spin and Charge Dynamics in Nanometer Ferromagnetic Heterostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12234267. [PMID: 36500890 PMCID: PMC9741209 DOI: 10.3390/nano12234267] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 06/12/2023]
Abstract
Due to its high sensitivity and because it does not rely on the magneto-optical response, terahertz (THz) emission spectroscopy has been used as a powerful time-resolved tool for investigating ultrafast demagnetization and spin current dynamics in nanometer-thick ferromagnetic (FM)/heavy metal (HM) heterostructures. Here, by changing the order of the conductive HM coating on the FM nanometer film, the dominant electric dipole contribution to the laser-induced THz radiation can be unraveled from the ultrafast magnetic dipole. Furthermore, to take charge equilibration into account, we separate the femtosecond laser-induced spin-to-charge converted current and the instantaneous discharging current within the illuminated area. The THz emission spectroscopy gives us direct information into the coupled spin and charge dynamics during the first moments of the light-matter interaction. Our results also open up new perspectives to manipulate and optimize the ultrafast charge current for promising high-performance and broadband THz radiation.
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Affiliation(s)
- Zhangshun Li
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Yexin Jiang
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Zuanming Jin
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Zhuoyi Li
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Xianyang Lu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Zhijiang Ye
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Jin-Yi Pang
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Yongbing Xu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Yan Peng
- Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
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13
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Scheuer L, Ruhwedel M, Karfaridis D, Vasileiadis IG, Sokoluk D, Torosyan G, Vourlias G, Dimitrakopoulos GP, Rahm M, Hillebrands B, Kehagias T, Beigang R, Papaioannou ET. THz emission from Fe/Pt spintronic emitters with L1 0-FePt alloyed interface. iScience 2022; 25:104319. [PMID: 35602944 PMCID: PMC9114522 DOI: 10.1016/j.isci.2022.104319] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 03/28/2022] [Accepted: 04/25/2022] [Indexed: 11/02/2022] Open
Abstract
Recent developments in nanomagnetism and spintronics have enabled the use of ultrafast spin physics for terahertz (THz) emission. Spintronic THz emitters, consisting of ferromagnetic (FM)/non-magnetic (NM) thin film heterostructures, have demonstrated impressive properties for the use in THz spectroscopy and have great potential in scientific and industrial applications. In this work, we focus on the impact of the FM/NM interface on the THz emission by investigating Fe/Pt bilayers with engineered interfaces. In particular, we intentionally modify the Fe/Pt interface by inserting an ordered L10-FePt alloy interlayer. Subsequently, we establish that a Fe/L10-FePt (2 nm)/Pt configuration is significantly superior to a Fe/Pt bilayer structure, regarding THz emission amplitude. The latter depends on the extent of alloying on either side of the interface. The unique trilayer structure opens new perspectives in terms of material choices for the next generation of spintronic THz emitters.
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Affiliation(s)
- Laura Scheuer
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Moritz Ruhwedel
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Dimitrios Karfaridis
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Isaak G Vasileiadis
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Dominik Sokoluk
- Fachbereich Elektro-Informationstechnik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Garik Torosyan
- Photonic Center Kaiserslautern, Kaiserslautern 67663, Germany
| | - George Vourlias
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | | | - Marco Rahm
- Fachbereich Elektro-Informationstechnik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Burkard Hillebrands
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Thomas Kehagias
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - René Beigang
- Fachbereich Physik, Technische Universität Kaiserslautern, Kaiserslautern 67663, Germany
| | - Evangelos Th Papaioannou
- Institut für Physik, Martin-Luther Universität Halle Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle, Germany
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14
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Chen X, Wang H, Liu H, Wang C, Wei G, Fang C, Wang H, Geng C, Liu S, Li P, Yu H, Zhao W, Miao J, Li Y, Wang L, Nie T, Zhao J, Wu X. Generation and Control of Terahertz Spin Currents in Topology-Induced 2D Ferromagnetic Fe 3 GeTe 2 |Bi 2 Te 3 Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106172. [PMID: 34816497 DOI: 10.1002/adma.202106172] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 11/10/2021] [Indexed: 06/13/2023]
Abstract
Future information technologies for low-dissipation quantum computation, high-speed storage, and on-chip communication applications require the development of atomically thin, ultracompact, and ultrafast spintronic devices in which information is encoded, stored, and processed using electron spin. Exploring low-dimensional magnetic materials, designing novel heterostructures, and generating and controlling ultrafast electron spin in 2D magnetism at room temperature, preferably in the unprecedented terahertz (THz) regime, is in high demand. Using THz emission spectroscopy driven by femtosecond laser pulses, optical THz spin-current bursts at room temperature in the 2D van der Waals ferromagnetic Fe3 GeTe2 (FGT) integrated with Bi2 Te3 as a topological insulator are successfully realized. The symmetry of the THz radiation is effectively controlled by the optical pumping incidence and external magnetic field directions, indicating that the THz generation mechanism is the inverse Edelstein effect contributed spin-to-charge conversion. Thickness-, temperature-, and structure-dependent nontrivial THz transients reveal that topology-enhanced interlayer exchange coupling increases the FGT Curie temperature to room temperature, which provides an effective approach for engineering THz spin-current pulses. These results contribute to the goal of all-optical generation, manipulation, and detection of ultrafast THz spin currents in room-temperature 2D magnetism, accelerating the development of atomically thin high-speed spintronic devices.
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Affiliation(s)
- Xinhou Chen
- School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China
| | - Hangtian Wang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Haijiang Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Chun Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Gaoshuai Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chan Fang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Hanchen Wang
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Chunyan Geng
- School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China
| | - Shaojie Liu
- School of Cyber Science and Technology, Beihang University, Beijing, 100191, China
| | - Peiyan Li
- School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China
| | - Haiming Yu
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Weisheng Zhao
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
- Hefei Innovation Research Institute, Beihang University, Hefei, 230013, China
| | - Jungang Miao
- School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China
| | - Yutong Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Li Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Tianxiao Nie
- Fert Beijing Institute, MIIT Key Laboratory of Spintronics, School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
- Hefei Innovation Research Institute, Beihang University, Hefei, 230013, China
| | - Jimin Zhao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Xiaojun Wu
- School of Electronic and Information Engineering, Beihang University, Beijing, 100191, China
- School of Cyber Science and Technology, Beihang University, Beijing, 100191, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
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15
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Fan F, Zhong C, Zhang Z, Li S, Chang S. Terahertz chiral sensing and magneto-optical enhancement for ferromagnetic nanofluids in the chiral metasurface. NANOSCALE ADVANCES 2021; 3:4790-4798. [PMID: 36134321 PMCID: PMC9417876 DOI: 10.1039/d1na00284h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 07/05/2021] [Indexed: 06/15/2023]
Abstract
The highly sensitive detection and magnetic field sensing of magnetic nanomaterials have received extensive attention, and its weak magneto-optical effect in the terahertz (THz) band limits its application. In this study, we investigated a chiral metasurface sensor filled with ferromagnetic nanofluids. Based on its artificial chiral resonance, the nanoparticle concentration and magneto-optical chiral response of the ferromagnetic nanofluids have both been detected using the THz time-domain polarization spectroscopy. The results show that the detection sensitivity of the concentration of the magnetic nanoparticles can reach 5.5 GHz %-1 by chiral sensing, needing only a trace amount of the nanofluid. More importantly, in this hybrid device, the magneto-optical chiral response of the ferromagnetic nanoparticles can be greatly enhanced by the chiral metasurface, which results in higher sensitivity to the external magnetic field. The Verdet constant of the ferromagnetic nanofluid in the metasurface is 15 times stronger than that without the chiral microstructure. This THz chiral sensing for nanoparticles and the chirality enhancement mechanism will promote a new sensing method and chiral manipulation device, especially for the highly sensitive magneto-optical device in the THz band.
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Affiliation(s)
- Fei Fan
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China
- Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China
| | - Changzhi Zhong
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China
| | - Ziyang Zhang
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China
| | - Shanshan Li
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China
| | - Shengjiang Chang
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Tianjin 300350 China
- Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China
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16
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Zhang W, Turchinovich D. Rigorous signal reconstruction in terahertz emission spectroscopy. OPTICS EXPRESS 2021; 29:24411-24421. [PMID: 34614687 DOI: 10.1364/oe.431739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Terahertz (THz) emission spectroscopy is a powerful method that allows one to measure the ultrafast dynamics of polarization, current, or magnetization in a material based on THz emission from the material. However, the practical implementation of this method can be challenging, and can result in significant errors in the reconstruction of the quantity of interest. Here, we experimentally and theoretically demonstrate a rigorous method of signal reconstruction in THz emission spectroscopy, and describe the main experimental and theoretical sources of reconstruction error. We identify the linear line-of-sight geometry of the THz emission spectrometer as the optimal configuration for accurate, fully calibrated THz signal reconstruction. As an example, we apply our reconstruction method to ultrafast THz magnetometry experiment, where we recover the ultrafast magnetization dynamics in a photoexcited iron film, including both its temporal shape and absolute magnitude.
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17
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Gueckstock O, Nádvorník L, Gradhand M, Seifert TS, Bierhance G, Rouzegar R, Wolf M, Vafaee M, Cramer J, Syskaki MA, Woltersdorf G, Mertig I, Jakob G, Kläui M, Kampfrath T. Terahertz Spin-to-Charge Conversion by Interfacial Skew Scattering in Metallic Bilayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006281. [PMID: 33506577 DOI: 10.1002/adma.202006281] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/24/2020] [Indexed: 06/12/2023]
Abstract
The efficient conversion of spin to charge transport and vice versa is of major relevance for the detection and generation of spin currents in spin-based electronics. Interfaces of heterostructures are known to have a marked impact on this process. Here, terahertz (THz) emission spectroscopy is used to study ultrafast spin-to-charge-current conversion (S2C) in about 50 prototypical F|N bilayers consisting of a ferromagnetic layer F (e.g., Ni81 Fe19 , Co, or Fe) and a nonmagnetic layer N with strong (Pt) or weak (Cu and Al) spin-orbit coupling. Varying the structure of the F/N interface leads to a drastic change in the amplitude and even inversion of the polarity of the THz charge current. Remarkably, when N is a material with small spin Hall angle, a dominant interface contribution to the ultrafast charge current is found. Its magnitude amounts to as much as about 20% of that found in the F|Pt reference sample. Symmetry arguments and first-principles calculations strongly suggest that the interfacial S2C arises from skew scattering of spin-polarized electrons at interface imperfections. The results highlight the potential of skew scattering for interfacial S2C and propose a promising route to enhanced S2C by tailored interfaces at all frequencies from DC to terahertz.
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Affiliation(s)
- Oliver Gueckstock
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Lukáš Nádvorník
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu 2027/3, Prague, 12116, Czech Republic
| | - Martin Gradhand
- School of Physics, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Tom Sebastian Seifert
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
- Department of Materials, ETH Zürich, Hönggerbergring 64, Zürich, 8093, Switzerland
| | - Genaro Bierhance
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Reza Rouzegar
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Martin Wolf
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
| | - Mehran Vafaee
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Joel Cramer
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Maria Andromachi Syskaki
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
- Singulus Technologies AG, 63796, Kahl am Main, Germany
| | - Georg Woltersdorf
- Institut für Physik, Martin-Luther-Universität Halle, Von-Danckelmann-Platz, 06120, Halle, Germany
| | - Ingrid Mertig
- Institut für Physik, Martin-Luther-Universität Halle, Von-Danckelmann-Platz, 06120, Halle, Germany
| | - Gerhard Jakob
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Mathias Kläui
- Institut für Physik, Johannes-Gutenberg-Universität Mainz, Staudingerweg 7, 55128, Mainz, Germany
| | - Tobias Kampfrath
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
- Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195, Berlin, Germany
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