1
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Isshiki H, Budai N, Kobayashi A, Uesugi R, Higo T, Nakatsuji S, Otani Y. Observation of Cluster Magnetic Octupole Domains in the Antiferromagnetic Weyl Semimetal Mn_{3}Sn Nanowire. PHYSICAL REVIEW LETTERS 2024; 132:216702. [PMID: 38856290 DOI: 10.1103/physrevlett.132.216702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 04/19/2024] [Indexed: 06/11/2024]
Abstract
The antiferromagnetic Weyl semimetal Mn_{3}Sn has attracted wide attention due to its vast anomalous transverse transport properties despite barely any net magnetization. So far, the magnetic properties of Mn_{3}Sn have been experimentally investigated on micrometer scale samples but not in nanometers. In this study, we measured the local anomalous Nernst effect of a (0001)-textured Mn_{3}Sn nanowire using a tip-contact-induced temperature gradient with an atomic force microscope. Our approach directly maps the distribution of the cluster magnetic octupole moments with 80 nm spatial resolution, providing crucial information for integrating the Mn_{3}Sn nanostructure into spintronic devices.
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Affiliation(s)
- Hironari Isshiki
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
| | - Nico Budai
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Ayuko Kobayashi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Ryota Uesugi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tomoya Higo
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
- Department of Physics, The University of Tokyo; Bunkyo-ku, Tokyo 113-0033, Japan
| | - Satoru Nakatsuji
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
- Department of Physics, The University of Tokyo; Bunkyo-ku, Tokyo 113-0033, Japan
- Trans-scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - YoshiChika Otani
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
- Trans-scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Center for Emergent Matter Science RIKEN, Wako, Saitama 51-0198, Japan
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2
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Zheng Z, Zeng T, Zhao T, Shi S, Ren L, Zhang T, Jia L, Gu Y, Xiao R, Zhou H, Zhang Q, Lu J, Wang G, Zhao C, Li H, Tay BK, Chen J. Effective electrical manipulation of a topological antiferromagnet by orbital torques. Nat Commun 2024; 15:745. [PMID: 38272914 PMCID: PMC10811228 DOI: 10.1038/s41467-024-45109-1] [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: 06/25/2023] [Accepted: 01/09/2024] [Indexed: 01/27/2024] Open
Abstract
The electrical control of the non-trivial topology in Weyl antiferromagnets is of great interest for the development of next-generation spintronic devices. Recent studies suggest that the spin Hall effect can switch the topological antiferromagnetic order. However, the switching efficiency remains relatively low. Here, we demonstrate the effective manipulation of antiferromagnetic order in the Weyl semimetal Mn3Sn using orbital torques originating from either metal Mn or oxide CuOx. Although Mn3Sn can convert orbital current to spin current on its own, we find that inserting a heavy metal layer, such as Pt, of appropriate thickness can effectively reduce the critical switching current density by one order of magnitude. In addition, we show that the memristor-like switching behaviour of Mn3Sn can mimic the potentiation and depression processes of a synapse with high linearity-which may be beneficial for constructing accurate artificial neural networks. Our work paves a way for manipulating the topological antiferromagnetic order and may inspire more high-performance antiferromagnetic functional devices.
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Affiliation(s)
- Zhenyi Zheng
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tao Zeng
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tieyang Zhao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Shu Shi
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Lizhu Ren
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Tongtong Zhang
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore, Singapore
| | - Lanxin Jia
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Youdi Gu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Rui Xiao
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Hengan Zhou
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Qihan Zhang
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Jiaqi Lu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Guilei Wang
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Chao Zhao
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China
| | - Huihui Li
- Beijing Superstring Academy of Memory Technology, Beijing, 100176, China.
| | - Beng Kang Tay
- Centre for Micro- and Nano-Electronics (CMNE), School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore, Singapore.
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore.
- Chongqing Research Institute, National University of Singapore, Chongqing, 401120, China.
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3
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Xie H, Zhang N, Ma Y, Chen X, Ke L, Wu Y. Efficient Noncollinear Antiferromagnetic State Switching Induced by the Orbital Hall Effect in Chromium. NANO LETTERS 2023; 23:10274-10281. [PMID: 37909311 DOI: 10.1021/acs.nanolett.3c02797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Recently, orbital Hall current has attracted attention as an alternative method to switch the magnetization of ferromagnets. Here we present our findings on electrical switching of the antiferromagnetic state in Mn3Sn/Cr, where despite the much smaller spin Hall angle of Cr, the switching current density is comparable to heavy metal-based heterostructures. However, the inverse process, i.e., spin-to-charge conversion in Cr-based heterostructures, is much less efficient than the Pt-based equivalents, as manifested in the 1 order of magnitude smaller terahertz emission intensity and spin current-induced magnetoresistance. These results in combination with the slow decay of terahertz emission against Cr thickness (diffusion length of ∼11 nm) suggest that the observed magnetic switching can be attributed to orbital current generation in Cr, followed by efficient conversion to spin current. Our work demonstrates the potential of light metals like Cr as efficient orbital/spin current sources for antiferromagnetic spintronics.
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Affiliation(s)
- Hang Xie
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Nan Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 138634, Singapore
| | - Yuteng Ma
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- National University of Singapore (Chong Qing) Research Institute, Chongqing Liang Jiang New Area, Chongqing 401123, China
| | - Xin Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Lin Ke
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 138634, Singapore
| | - Yihong Wu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
- National University of Singapore (Chong Qing) Research Institute, Chongqing Liang Jiang New Area, Chongqing 401123, China
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4
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Tahir M, Chen H. Transport of Spin Magnetic Multipole Moments Carried by Bloch Quasiparticles. PHYSICAL REVIEW LETTERS 2023; 131:106701. [PMID: 37739362 DOI: 10.1103/physrevlett.131.106701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 03/31/2023] [Accepted: 08/08/2023] [Indexed: 09/24/2023]
Abstract
Magnetic ordering beyond the standard dipolar order has attracted significant attention in recent years, but it remains an open question how to effectively manipulate such nontrivial order parameters using external perturbations such as electric currents or fields. In particular, it is desirable to have a conceptual tool similar to nonequilibrium spin currents in spintronics to describe the creation and transport of multipole moments. In this context, we present a theory for Cartesian spin magnetic multipole moments of Bloch quasiparticles and their transport based on a general gauge-invariant formula obtained using the wave packet approach. As a concrete example, we point out that the low-energy Hamiltonian of phosphorene subject to a perpendicular electric field has a valley structure that hosts magnetic octupole moments. The magnetic octupole moments can be exhibited by an in-plane electric current and lead to accumulation of staggered spin densities at the corners of a rectangular sample. Our Letter paves the way for systematically seeking and utilizing quasiparticles with higher-order magnetic multipole moments in crystal materials towards the emergence of multipoletronics.
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Affiliation(s)
- Muhammad Tahir
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Hua Chen
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
- School of Advanced Materials Discovery, Colorado State University, Fort Collins, Colorado 80523, USA
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5
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Yoon JY, Zhang P, Chou CT, Takeuchi Y, Uchimura T, Hou JT, Han J, Kanai S, Ohno H, Fukami S, Liu L. Handedness anomaly in a non-collinear antiferromagnet under spin-orbit torque. NATURE MATERIALS 2023; 22:1106-1113. [PMID: 37537356 DOI: 10.1038/s41563-023-01620-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/23/2023] [Indexed: 08/05/2023]
Abstract
Non-collinear antiferromagnets are an emerging family of spintronic materials because they not only possess the general advantages of antiferromagnets but also enable more advanced functionalities. Recently, in an intriguing non-collinear antiferromagnet Mn3Sn, where the octupole moment is defined as the collective magnetic order parameter, spin-orbit torque (SOT) switching has been achieved in seemingly the same protocol as in ferromagnets. Nevertheless, it is fundamentally important to explore the unknown octupole moment dynamics and contrast it with the magnetization vector of ferromagnets. Here we report a handedness anomaly in the SOT-driven dynamics of Mn3Sn: when spin current is injected, the octupole moment rotates in the opposite direction to the individual moments, leading to a SOT switching polarity distinct from ferromagnets. By using second-harmonic and d.c. magnetometry, we track the SOT effect onto the octupole moment during its rotation and reveal that the handedness anomaly stems from the interactions between the injected spin and the unique chiral-spin structure of Mn3Sn. We further establish the torque balancing equation of the magnetic octupole moment and quantify the SOT efficiency. Our finding provides a guideline for understanding and implementing the electrical manipulation of non-collinear antiferromagnets, which in nature differs from the well-established collinear magnets.
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Affiliation(s)
- Ju-Young Yoon
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Pengxiang Zhang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chung-Tao Chou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yutaro Takeuchi
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Tomohiro Uchimura
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Justin T Hou
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jiahao Han
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
| | - Shun Kanai
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Division for the Establishment of Frontier Sciences of Organization for Advanced Studies, Tohoku University, Sendai, Japan
| | - Hideo Ohno
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Graduate School of Engineering, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan
| | - Shunsuke Fukami
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
- Graduate School of Engineering, Tohoku University, Sendai, Japan.
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan.
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan.
- Inamori Research Institute for Science, Kyoto, Japan.
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
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6
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Han J, Cheng R, Liu L, Ohno H, Fukami S. Coherent antiferromagnetic spintronics. NATURE MATERIALS 2023; 22:684-695. [PMID: 36941390 DOI: 10.1038/s41563-023-01492-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 01/25/2023] [Indexed: 06/03/2023]
Abstract
Antiferromagnets have attracted extensive interest as a material platform in spintronics. So far, antiferromagnet-enabled spin-orbitronics, spin-transfer electronics and spin caloritronics have formed the bases of antiferromagnetic spintronics. Spin transport and manipulation based on coherent antiferromagnetic dynamics have recently emerged, pushing the developing field of antiferromagnetic spintronics towards a new stage distinguished by the features of spin coherence. In this Review, we categorize and analyse the critical effects that harness the coherence of antiferromagnets for spintronic applications, including spin pumping from monochromatic antiferromagnetic magnons, spin transmission via phase-correlated antiferromagnetic magnons, electrically induced spin rotation and ultrafast spin-orbit effects in antiferromagnets. We also discuss future opportunities in research and applications stimulated by the principles, materials and phenomena of coherent antiferromagnetic spintronics.
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Affiliation(s)
- Jiahao Han
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
| | - Ran Cheng
- Department of Electrical and Computer Engineering, University of California Riverside, Riverside, CA, USA
- Department of Physics and Astronomy, University of California Riverside, Riverside, CA, USA
| | - Luqiao Liu
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Hideo Ohno
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan
| | - Shunsuke Fukami
- Research Institute of Electrical Communication, Tohoku University, Sendai, Japan.
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai, Japan.
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai, Japan.
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, Japan.
- Inamori Research Institute of Science, Kyoto, Japan.
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7
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Niu Y, Lv H, Wu X, Yang J. Electric-Field Control of Spin Polarization above Room Temperature in Single-Layer A-Type Antiferromagnetic Semiconductor. J Phys Chem Lett 2023; 14:4042-4049. [PMID: 37093651 DOI: 10.1021/acs.jpclett.3c00883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Two-dimensional (2D) antiferromagnets have drawn great interest for absence of stray fields in antiferromagnetic (AFM) spintronics. However, it remains challenging to manipulate their spin polarization above room temperature for practical applications. Herein, a general strategy is reported to realize the control of spin polarization above room temperature in 2D A-type AFM semiconductors by external electric field based on first-principles calculations, exemplified by transition metal monohalide MnCl and carbide MXenes Cr2CX2 (X = F, Cl, OH). It shows that 100% spin polarization can be induced around Fermi level with spin splitting gap related to the spatial distribution of spin density in real space. Meanwhile, the Neél temperature of 2D MnCl and Cr2CF2 remains above room temperature under external electric field up to 0.6 V/Å. This study exhibits the potential for application of 2D AFM semiconductors in electric-field-controlled spintronics.
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Affiliation(s)
- Yijie Niu
- CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Science, CAS Center for Excellence in Nanoscience, and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Haifeng Lv
- CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Science, CAS Center for Excellence in Nanoscience, and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaojun Wu
- CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Science, CAS Center for Excellence in Nanoscience, and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui 230088, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Jinlong Yang
- CAS Key Laboratory of Materials for Energy Conversion, School of Chemistry and Materials Science, CAS Center for Excellence in Nanoscience, and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
- Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui 230088, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
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8
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Wang X, Zhou X, Yan H, Qin P, Chen H, Meng Z, Feng Z, Liu L, Liu Z. Topological Hall Effect in Thin Films of an Antiferromagnetic Weyl Semimetal Integrated on Si. ACS APPLIED MATERIALS & INTERFACES 2023; 15:7572-7577. [PMID: 36700918 DOI: 10.1021/acsami.2c20644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Since the large room-temperature anomalous Hall effect was discovered in noncollinear antiferromagnets, Mn3Sn has received immense research interest as it exhibits abundant exotic physical properties including Weyl points and enormous potential for antiferromagnetic spintronic device applications. In this work, we report the emergence of the topological Hall effect in Mn3Sn films grown on Si that is the workhorse for the modern highly integrated information technology. Importantly, through a series of systematic comparative experiments, the intriguing topological Hall effect phenomenon related to the appearance of the noncoplanar chiral spin structure is found to be induced by the Mn3Sn/SiO2 interface. Furthermore, it was found that the current injection to a Pt/Mn3Sn bilayer Hall bar device can effectively manipulate the chiral spin structure of Mn3Sn, which demonstrates the feasibility of Si-based noncollinear antiferromagnetic spintronics.
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Affiliation(s)
- Xiaoning Wang
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Xiaorong Zhou
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Han Yan
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Peixin Qin
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Hongyu Chen
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Ziang Meng
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Zexin Feng
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Li Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
| | - Zhiqi Liu
- School of Materials Science and Engineering, Beihang University, Beijing 100191, China
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9
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Abstract
Relaxometry is a technique which makes use of a specific crystal lattice defect in diamond, the so-called NV center. This defect consists of a nitrogen atom, which replaces a carbon atom in the diamond lattice, and an adjacent vacancy. NV centers allow converting magnetic noise into optical signals, which dramatically increases the sensitivity of the readout, allowing for nanoscale resolution. Analogously to T1 measurements in conventional magnetic resonance imaging (MRI), relaxometry allows the detection of different concentrations of paramagnetic species. However, since relaxometry allows very local measurements, the detected signals are from nanoscale voxels around the NV centers. As a result, it is possible to achieve subcellular resolutions and organelle specific measurements.A relaxometry experiment starts with polarizing the spins of NV centers in the diamond lattice, using a strong laser pulse. Afterward the laser is switched off and the NV centers are allowed to stochastically decay into the equilibrium mix of different magnetic states. The polarized configuration exhibits stronger fluorescence than the equilibrium state, allowing one to optically monitor this transition and determine its rate. This process happens faster at higher levels of magnetic noise. Alternatively, it is possible to conduct T1 relaxation measurements from the dark to the bright equilibrium by applying a microwave pulse which brings NV centers into the -1 state instead of the 0 state. One can record a spectrum of T1 at varying strengths of the applied magnetic field. This technique is called cross-relaxometry. Apart from detecting magnetic signals, responsive coatings can be applied which render T1 sensitive to other parameters as pH, temperature, or electric field. Depending on the application there are three different ways to conduct relaxometry experiments: relaxometry in moving or stationary nanodiamonds, scanning magnetometry, and relaxometry in a stationary bulk diamond with a stationary sample on top.In this Account, we present examples for various relaxometry modes as well as their advantages and limitations. Due to the simplicity and low cost of the approach, relaxometry has been implemented in many different instruments and for a wide range of applications. Herein we review the progress that has been achieved in physics, chemistry, and biology. Many articles in this field have a proof-of-principle character, and the full potential of the technology still waits to be unfolded. With this Account, we would like to stimulate discourse on the future of relaxometry.
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Affiliation(s)
- Aldona Mzyk
- Groningen
University, University Medical
Center Groningen, Antonius
Deusinglaan 1, 9713AW Groningen, the Netherlands,Institute
of Metallurgy and Materials Science, Polish Academy of Sciences, ul. Reymonta 25, 30-059 Kraków, Poland
| | - Alina Sigaeva
- Groningen
University, University Medical
Center Groningen, Antonius
Deusinglaan 1, 9713AW Groningen, the Netherlands
| | - Romana Schirhagl
- Groningen
University, University Medical
Center Groningen, Antonius
Deusinglaan 1, 9713AW Groningen, the Netherlands,
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10
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Erickson A, Abbas Shah SQ, Mahmood A, Fescenko I, Timalsina R, Binek C, Laraoui A. Nanoscale imaging of antiferromagnetic domains in epitaxial films of Cr 2O 3 via scanning diamond magnetic probe microscopy. RSC Adv 2022; 13:178-185. [PMID: 36605625 PMCID: PMC9764058 DOI: 10.1039/d2ra06440e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/05/2022] [Indexed: 01/07/2023] Open
Abstract
We report direct imaging of boundary magnetization associated with antiferromagnetic domains in magnetoelectric epitaxial Cr2O3 thin films using diamond nitrogen vacancy microscopy. We found a correlation between magnetic domain size and structural grain size which we associate with the domain formation process. We performed field cooling, i.e., cooling from above to below the Néel temperature in the presence of a magnetic field, which resulted in the selection of one of the two otherwise degenerate 180° domains. Lifting of such a degeneracy is achievable with a magnetic field alone due to the Zeeman energy of a weak parasitic magnetic moment in Cr2O3 films that originates from defects and the imbalance of the boundary magnetization of opposing interfaces. This boundary magnetization couples to the antiferromagnetic order parameter enabling selection of its orientation. Nanostructuring the Cr2O3 film with mesa structures revealed reversible edge magnetic states with the direction of magnetic field during field cooling.
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Affiliation(s)
- Adam Erickson
- Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln900 N 16th St., W342 NHLincolnNebraska 68588USA
| | - Syed Qamar Abbas Shah
- Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln855 N 16th StLincolnNebraska 68588USA
| | - Ather Mahmood
- Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln855 N 16th StLincolnNebraska 68588USA
| | - Ilja Fescenko
- Laser Center, University of LatviaJelgavas St 3RigaLV-1004Latvia
| | - Rupak Timalsina
- Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln900 N 16th St., W342 NHLincolnNebraska 68588USA
| | - Christian Binek
- Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln855 N 16th StLincolnNebraska 68588USA
| | - Abdelghani Laraoui
- Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln900 N 16th St., W342 NHLincolnNebraska 68588USA,Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln855 N 16th StLincolnNebraska 68588USA
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11
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Xie H, Chen X, Zhang Q, Mu Z, Zhang X, Yan B, Wu Y. Magnetization switching in polycrystalline Mn 3Sn thin film induced by self-generated spin-polarized current. Nat Commun 2022; 13:5744. [PMID: 36180425 PMCID: PMC9525633 DOI: 10.1038/s41467-022-33345-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Electrical manipulation of spins is essential to design state-of-the-art spintronic devices and commonly relies on the spin current injected from a second heavy-metal material. The fact that chiral antiferromagnets produce spin current inspires us to explore the magnetization switching of chiral spins using self-generated spin torque. Here, we demonstrate the electric switching of noncollinear antiferromagnetic state in Mn3Sn by observing a crossover from conventional spin-orbit torque to the self-generated spin torque when increasing the MgO thickness in Ta/MgO/Mn3Sn polycrystalline films. The spin current injection from the Ta layer can be controlled and even blocked by varying the MgO thickness, but the switching sustains even at a large MgO thickness. Furthermore, the switching polarity reverses when the MgO thickness exceeds around 3 nm, which cannot be explained by the spin-orbit torque scenario due to spin current injection from the Ta layer. Evident current-induced switching is also observed in MgO/Mn3Sn and Ti/Mn3Sn bilayers, where external injection of spin Hall current to Mn3Sn is negligible. The inter-grain spin-transfer torque induced by spin-polarized current explains the experimental observations. Our findings provide an alternative pathway for electrical manipulation of non-collinear antiferromagnetic state without resorting to the conventional bilayer structure. Under an applied current, chiral antiferromagnets, such as Mn3Sn, can produce a spin-polarized current. Here, by varying the thickness of a buffering layer, the authors show that this spin-polarized current can drive self-induced switching in polycrystalline Mn3Sn.
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Affiliation(s)
- Hang Xie
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Xin Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Qi Zhang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.,Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Xueyuan Rd. 1088, Shenzhen, 518055, China
| | - Zhiqiang Mu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Xinhai Zhang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Xueyuan Rd. 1088, Shenzhen, 518055, China
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 7610001, Israel.
| | - Yihong Wu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore.
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