1
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Coherent correlation imaging for resolving fluctuating states of matter. Nature 2023; 614:256-261. [PMID: 36653456 PMCID: PMC9908557 DOI: 10.1038/s41586-022-05537-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/08/2022] [Indexed: 01/19/2023]
Abstract
Fluctuations and stochastic transitions are ubiquitous in nanometre-scale systems, especially in the presence of disorder. However, their direct observation has so far been impeded by a seemingly fundamental, signal-limited compromise between spatial and temporal resolution. Here we develop coherent correlation imaging (CCI) to overcome this dilemma. Our method begins by classifying recorded camera frames in Fourier space. Contrast and spatial resolution emerge by averaging selectively over same-state frames. Temporal resolution down to the acquisition time of a single frame arises independently from an exceptionally low misclassification rate, which we achieve by combining a correlation-based similarity metric1,2 with a modified, iterative hierarchical clustering algorithm3,4. We apply CCI to study previously inaccessible magnetic fluctuations in a highly degenerate magnetic stripe domain state with nanometre-scale resolution. We uncover an intricate network of transitions between more than 30 discrete states. Our spatiotemporal data enable us to reconstruct the pinning energy landscape and to thereby explain the dynamics observed on a microscopic level. CCI massively expands the potential of emerging high-coherence X-ray sources and paves the way for addressing large fundamental questions such as the contribution of pinning5-8 and topology9-12 in phase transitions and the role of spin and charge order fluctuations in high-temperature superconductivity13,14.
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2
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Causal analysis and visualization of magnetization reversal using feature extended landau free energy. Sci Rep 2022; 12:19892. [DOI: 10.1038/s41598-022-21971-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/06/2022] [Indexed: 11/30/2022] Open
Abstract
AbstractThe magnetization reversal in nanomagnets is causally analyzed using an extended Landau free-energy model. This model draws an energy landscape in the information space using physics-based features. Thus, the origin of the magnetic effect in macroscopic pinning phenomena can be identified. The microscopic magnetic domain beyond the hierarchy can be explained using energy gradient analysis and its decomposition. Structural features from the magnetic domains are extracted using persistent homology. Extended energy is visualized using ridge regression, principal component analysis, and Hadamard products. We found that the demagnetization energy concentration near a defect causes the demagnetization effect, which quantitatively dominates the pinning phenomenon. The exchange energy inhibits pinning, promotes saturation, and shows slight interactions with the defect. Furthermore, the energy distributions are visualized in real space. Left-position defects reduce the energy barrier and are useful for the topological inverse design of recording devices.
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3
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Magnetic Barkhausen Noise Transient Analysis for Microstructure Evolution Characterization with Tensile Stress in Elastic and Plastic Status. SENSORS 2021; 21:s21248310. [PMID: 34960403 PMCID: PMC8706020 DOI: 10.3390/s21248310] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 11/17/2022]
Abstract
Stress affects the microstructure of the material to influence the durability and service life of the components. However, the previous work of stress measurement lacks quantification of the different variations in time and spatial features of micromagnetic properties affected by stress in elastic and plastic ranges, as well as the evolution of microstructure. In this paper, microstructure evolution under stress in elastic and plastic ranges is evaluated by magnetic Barkhausen noise (MBN) transient analysis. Based on a J-A model, the duration and the intensity are the eigenvalues for MBN transient analysis to quantify transient size and number of Barkhausen events under stress. With the observation of domain wall (DW) distribution and microstructure, the correlation between material microstructure and MBN transient eigenvalues is investigated to verify the ability of material status evaluation on the microscopic scale of the method. The results show that the duration and the intensity have different change trends in elastic and plastic ranges. The eigenvalue fusion of the duration and intensity distinguishes the change in microstructure under the stress in elastic and plastic deformation. The appearance of grain boundary (GB) migration and dislocation under the stress in the plastic range makes the duration and the intensity higher on the GB than those inside the grain. Besides, the reproducibility of the proposed method is investigated by evaluating microstructure evolution for silicon steel sheet and Q235 steel sheet. The proposed method investigates the correlation between the microstructure and transient micromagnetic properties, which has the potential for stress evaluation in elastic and plastic ranges for industrial materials.
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4
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Precision Magnetometers for Aerospace Applications: A Review. SENSORS 2021; 21:s21165568. [PMID: 34451010 PMCID: PMC8402258 DOI: 10.3390/s21165568] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/02/2021] [Accepted: 08/10/2021] [Indexed: 11/17/2022]
Abstract
Aerospace technologies are crucial for modern civilization; space-based infrastructure underpins weather forecasting, communications, terrestrial navigation and logistics, planetary observations, solar monitoring, and other indispensable capabilities. Extraplanetary exploration—including orbital surveys and (more recently) roving, flying, or submersible unmanned vehicles—is also a key scientific and technological frontier, believed by many to be paramount to the long-term survival and prosperity of humanity. All of these aerospace applications require reliable control of the craft and the ability to record high-precision measurements of physical quantities. Magnetometers deliver on both of these aspects and have been vital to the success of numerous missions. In this review paper, we provide an introduction to the relevant instruments and their applications. We consider past and present magnetometers, their proven aerospace applications, and emerging uses. We then look to the future, reviewing recent progress in magnetometer technology. We particularly focus on magnetometers that use optical readout, including atomic magnetometers, magnetometers based on quantum defects in diamond, and optomechanical magnetometers. These optical magnetometers offer a combination of field sensitivity, size, weight, and power consumption that allows them to reach performance regimes that are inaccessible with existing techniques. This promises to enable new applications in areas ranging from unmanned vehicles to navigation and exploration.
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5
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Liu J, Tian G, Gao B, Zeng K, Xu Y, Liu Q. Time-Response-Histogram-Based Feature of Magnetic Barkhausen Noise for Material Characterization Considering Influences of Grain and Grain Boundary under In Situ Tensile Test. SENSORS 2021; 21:s21072350. [PMID: 33800570 PMCID: PMC8037368 DOI: 10.3390/s21072350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/02/2022]
Abstract
Stress is the crucial factor of ferromagnetic material failure origin. However, the nondestructive test methods to analyze the ferromagnetic material properties’ inhomogeneity on the microscopic scale with stress have not been obtained so far. In this study, magnetic Barkhausen noise (MBN) signals on different silicon steel sheet locations under in situ tensile tests were detected by a high-spatial-resolution magnetic probe. The domain-wall (DW) motion, grain, and grain boundary were detected using a magneto-optical Kerr (MOKE) image. The time characteristic of DW motion and MBN signals on different locations was varied during elastic deformation. Therefore, a time-response histogram is proposed in this work to show different DW motions inside the grain and around the grain boundary under low tensile stress. In order to separate the variation of magnetic properties affected by the grain and grain boundary under low tensile stress corresponding to MBN excitation, time-division was carried out to extract the root-mean-square (RMS), mean, and peak in the optimized time interval. The time-response histogram of MBN evaluated the silicon steel sheet’s inhomogeneous material properties, and provided a theoretical and experimental reference for ferromagnetic material properties under stress.
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Affiliation(s)
- Jia Liu
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (B.G.); (K.Z.); (Q.L.)
- Correspondence: (J.L.); (G.T.)
| | - Guiyun Tian
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (B.G.); (K.Z.); (Q.L.)
- School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
- Correspondence: (J.L.); (G.T.)
| | - Bin Gao
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (B.G.); (K.Z.); (Q.L.)
| | - Kun Zeng
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (B.G.); (K.Z.); (Q.L.)
| | - Yongbing Xu
- Spintronics and Nanodevice Laboratory, Department of Electronics Engineering, University of York, York YO10 5DD, UK;
| | - Qianhang Liu
- School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China; (B.G.); (K.Z.); (Q.L.)
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6
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Holl C, Knol M, Pratzer M, Chico J, Fernandes IL, Lounis S, Morgenstern M. Probing the pinning strength of magnetic vortex cores with sub-nanometer resolution. Nat Commun 2020; 11:2833. [PMID: 32504062 PMCID: PMC7275073 DOI: 10.1038/s41467-020-16701-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/20/2020] [Indexed: 11/28/2022] Open
Abstract
Understanding interactions of magnetic textures with defects is crucial for applications such as racetrack memories or microwave generators. Such interactions appear on the few nanometer scale, where imaging has not yet been achieved with controlled external forces. Here, we establish a method determining such interactions via spin-polarized scanning tunneling microscopy in three-dimensional magnetic fields. We track a magnetic vortex core, pushed by the forces of the in-plane fields, and discover that the core (~ 104 Fe-atoms) gets successively pinned close to single atomic-scale defects. Reproducing the core path along several defects via parameter fit, we deduce the pinning potential as a mexican hat with short-range repulsive and long-range attractive part. The approach to deduce defect induced pinning potentials on the sub-nanometer scale is transferable to other non-collinear spin textures, eventually enabling an atomic scale design of defect configurations for guiding and reliable read-out in race-track type devices. Magnetic vortices such as skyrmions are promising for spintronic applications, however, little is known about the pinning effects strongly influencing their dynamics. Here, the authors map the interaction potential between defects and vortex cores down to the sub-nanometer scale enabling the better control of these magnetic textures.
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Affiliation(s)
- Christian Holl
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, D-52074, Aachen, Germany
| | - Marvin Knol
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, D-52074, Aachen, Germany
| | - Marco Pratzer
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, D-52074, Aachen, Germany
| | - Jonathan Chico
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Imara Lima Fernandes
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425, Jülich, Germany
| | - Markus Morgenstern
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, D-52074, Aachen, Germany.
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7
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Delord T, Huillery P, Nicolas L, Hétet G. Spin-cooling of the motion of a trapped diamond. Nature 2020; 580:56-59. [DOI: 10.1038/s41586-020-2133-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 01/17/2020] [Indexed: 11/09/2022]
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8
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Gonzalez-Ballestero C, Gieseler J, Romero-Isart O. Quantum Acoustomechanics with a Micromagnet. PHYSICAL REVIEW LETTERS 2020; 124:093602. [PMID: 32202851 DOI: 10.1103/physrevlett.124.093602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 02/06/2020] [Indexed: 06/10/2023]
Abstract
We show theoretically how to strongly couple the center-of-mass motion of a micromagnet in a harmonic potential to one of its acoustic phononic modes. The coupling is induced by a combination of an oscillating magnetic field gradient and a static homogeneous magnetic field. The former parametrically couples the center-of-mass motion to a magnonic mode while the latter tunes the magnonic mode in resonance with a given acoustic phononic mode. The magnetic fields can be adjusted to either cool the center-of-mass motion to the ground state or to enter into the strong quantum coupling regime. The center of mass can thus be used to probe and manipulate an acoustic mode, thereby opening new possibilities for out-of-equilibrium quantum mesoscopic physics. Our results hold for experimentally feasible parameters and apply to levitated micromagnets as well as micromagnets deposited on a clamped nanomechanical oscillator.
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Affiliation(s)
- Carlos Gonzalez-Ballestero
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Jan Gieseler
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Oriol Romero-Isart
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
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9
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Silva RL, Silva RC, Pereira AR, Moura-Melo WA. Antiferromagnetic skyrmions overcoming obstacles in a racetrack. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:225802. [PMID: 30808010 DOI: 10.1088/1361-648x/ab0abd] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Topological objects interacting with lattice defects is an important topic in condensed matter physics. In this paper, we would like to explore the ballistic trajectory of an antiferromagnetic skyrmion in a racetrack to study processes such as collisions of skyrmions and holes in the magnetic sample. The skyrmion is impelled against the hole-obstacle by means of a spin polarized current. Depending on the skyrmion velocity (associated to the strength of the applied current) and the type of collision (frontal or lateral), it will be captured, scattered or completely destroyed by the hole. In some cases, this obstacle can shift the skyrmion center from a straight line to another one, and it appears as an effective way of manipulating skyrmion trajectories and dynamics.
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Affiliation(s)
- R L Silva
- Departamento de Ciências Naturais, Universidade Federal do Espírito Santo, São Mateus, ES, 29932-540, Brazil
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10
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Fernández-Pacheco A, Streubel R, Fruchart O, Hertel R, Fischer P, Cowburn RP. Three-dimensional nanomagnetism. Nat Commun 2017; 8:15756. [PMID: 28598416 PMCID: PMC5494189 DOI: 10.1038/ncomms15756] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 04/20/2017] [Indexed: 01/18/2023] Open
Abstract
Magnetic nanostructures are being developed for use in many aspects of our daily life, spanning areas such as data storage, sensing and biomedicine. Whereas patterned nanomagnets are traditionally two-dimensional planar structures, recent work is expanding nanomagnetism into three dimensions; a move triggered by the advance of unconventional synthesis methods and the discovery of new magnetic effects. In three-dimensional nanomagnets more complex magnetic configurations become possible, many with unprecedented properties. Here we review the creation of these structures and their implications for the emergence of new physics, the development of instrumentation and computational methods, and exploitation in numerous applications. Nanoscale magnetic devices play a key role in modern technologies but current applications involve only 2D structures like magnetic discs. Here the authors review recent progress in the fabrication and understanding of 3D magnetic nanostructures, enabling more diverse functionalities.
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Affiliation(s)
| | - Robert Streubel
- Division of Materials Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Olivier Fruchart
- Univ. Grenoble Alpes, CNRS, CEA, Grenoble INP, INAC, SPINTEC, F-38000 Grenoble, France
| | - Riccardo Hertel
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Department of Magnetic Objects on the Nanoscale, F-67000 Strasbourg, France
| | - Peter Fischer
- Division of Materials Sciences, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Physics, UC Santa Cruz, Santa Cruz, California 95064, USA
| | - Russell P Cowburn
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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11
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Wu M, Wu NLY, Firdous T, Fani Sani F, Losby JE, Freeman MR, Barclay PE. Nanocavity optomechanical torque magnetometry and radiofrequency susceptometry. NATURE NANOTECHNOLOGY 2017; 12:127-131. [PMID: 27798605 DOI: 10.1038/nnano.2016.226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 09/19/2016] [Indexed: 06/06/2023]
Abstract
Nanophotonic optomechanical devices allow the observation of nanoscale vibrations with a sensitivity that has dramatically advanced the metrology of nanomechanical structures and has the potential to impact studies of nanoscale physical systems in a similar manner. Here we demonstrate this potential with a nanophotonic optomechanical torque magnetometer and radiofrequency (RF) magnetic susceptometer. Exquisite readout sensitivity provided by a nanocavity integrated within a torsional nanomechanical resonator enables observations of the unique net magnetization and RF-driven responses of single mesoscopic magnetic structures in ambient conditions. The magnetic moment resolution is sufficient for the observation of Barkhausen steps in the magnetic hysteresis of a lithographically patterned permalloy island. In addition, significantly enhanced RF susceptibility is found over narrow field ranges and attributed to thermally assisted driven hopping of a magnetic vortex core between neighbouring pinning sites. The on-chip magnetosusceptometer scheme offers a promising path to powerful integrated cavity optomechanical devices for the quantitative characterization of magnetic micro- and nanosystems in science and technology.
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Affiliation(s)
- Marcelo Wu
- Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
| | - Nathanael L-Y Wu
- Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
| | - Tayyaba Firdous
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Fatemeh Fani Sani
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Joseph E Losby
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Mark R Freeman
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Paul E Barclay
- Department of Physics and Astronomy and Institute for Quantum Science and Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
- National Institute for Nanotechnology, Edmonton, Alberta T6G 2M9, Canada
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12
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Kim PH, Hauer BD, Doolin C, Souris F, Davis JP. Approaching the standard quantum limit of mechanical torque sensing. Nat Commun 2016; 7:13165. [PMID: 27762273 PMCID: PMC5080439 DOI: 10.1038/ncomms13165] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/07/2016] [Indexed: 11/23/2022] Open
Abstract
Reducing the moment of inertia improves the sensitivity of a mechanically based torque sensor, the parallel of reducing the mass of a force sensor, yet the correspondingly small displacements can be difficult to measure. To resolve this, we incorporate cavity optomechanics, which involves co-localizing an optical and mechanical resonance. With the resulting enhanced readout, cavity-optomechanical torque sensors are now limited only by thermal noise. Further progress requires thermalizing such sensors to low temperatures, where sensitivity limitations are instead imposed by quantum noise. Here, by cooling a cavity-optomechanical torque sensor to 25 mK, we demonstrate a torque sensitivity of 2.9 yNm/. At just over a factor of ten above its quantum-limited sensitivity, such cryogenic optomechanical torque sensors will enable both static and dynamic measurements of integrated samples at the level of a few hundred spins.
Cavity optomechanics enables measurement of torque at levels unattainable by previous techniques, but the main obstacle to improved sensitivity is thermal noise. Here the authors present cryogenic measurement of a cavity-optomechanical torsional resonator with unprecedented torque sensitivity of 2.9 yNm/√Hz.
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Affiliation(s)
- P H Kim
- Department of Physics, University of Alberta, CCIS 3-199, Edmonton, Alberta, Canada T6G 2E9
| | - B D Hauer
- Department of Physics, University of Alberta, CCIS 3-199, Edmonton, Alberta, Canada T6G 2E9
| | - C Doolin
- Department of Physics, University of Alberta, CCIS 3-199, Edmonton, Alberta, Canada T6G 2E9
| | - F Souris
- Department of Physics, University of Alberta, CCIS 3-199, Edmonton, Alberta, Canada T6G 2E9
| | - J P Davis
- Department of Physics, University of Alberta, CCIS 3-199, Edmonton, Alberta, Canada T6G 2E9
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13
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He L, Li H, Li M. Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices. SCIENCE ADVANCES 2016; 2:e1600485. [PMID: 27626072 PMCID: PMC5017824 DOI: 10.1126/sciadv.1600485] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 08/04/2016] [Indexed: 05/14/2023]
Abstract
Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon's polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry.
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14
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Leliaert J, Van de Wiele B, Vansteenkiste A, Laurson L, Durin G, Dupré L, Van Waeyenberge B. Creep turns linear in narrow ferromagnetic nanostrips. Sci Rep 2016; 6:20472. [PMID: 26843125 PMCID: PMC4740894 DOI: 10.1038/srep20472] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/04/2016] [Indexed: 11/10/2022] Open
Abstract
The motion of domain walls in magnetic materials is a typical example of a creep process, usually characterised by a stretched exponential velocity-force relation. By performing large-scale micromagnetic simulations, and analyzing an extended 1D model which takes the effects of finite temperatures and material defects into account, we show that this creep scaling law breaks down in sufficiently narrow ferromagnetic strips. Our analysis of current-driven transverse domain wall motion in disordered Permalloy nanostrips reveals instead a creep regime with a linear dependence of the domain wall velocity on the applied field or current density. This originates from the essentially point-like nature of domain walls moving in narrow, line- like disordered nanostrips. An analogous linear relation is found also by analyzing existing experimental data on field-driven domain wall motion in perpendicularly magnetised media.
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Affiliation(s)
- Jonathan Leliaert
- Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium.,Department of Electrical Energy, Systems and Automation, Ghent University, 9000 Ghent, Belgium
| | - Ben Van de Wiele
- Department of Electrical Energy, Systems and Automation, Ghent University, 9000 Ghent, Belgium
| | - Arne Vansteenkiste
- Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium
| | - Lasse Laurson
- COMP Centre of Excellence and Helsinki Institute of Physics, Department of Applied Physics, Aalto University, P.O. Box 11100, FIN-00076 Aalto, Espoo, Finland
| | - Gianfranco Durin
- Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino, Italy.,ISI Foundation, Via Alassio 11/c, 10126, Torino, Italy
| | - Luc Dupré
- Department of Electrical Energy, Systems and Automation, Ghent University, 9000 Ghent, Belgium
| | - Bartel Van Waeyenberge
- Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium
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15
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Losby JE, Sani FF, Grandmont DT, Diao Z, Belov M, Burgess JAJ, Compton SR, Hiebert WK, Vick D, Mohammad K, Salimi E, Bridges GE, Thomson DJ, Freeman MR. Torque-mixing magnetic resonance spectroscopy. Science 2015; 350:798-801. [DOI: 10.1126/science.aad2449] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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16
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Tian F, Zhou G, Chau FS, Deng J. Torsional optical spring effect in coupled nanobeam photonic crystal cavities. OPTICS LETTERS 2014; 39:6289-6292. [PMID: 25361336 DOI: 10.1364/ol.39.006289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Compared to probe-tuned optomechanical cavity systems, coupled cavity systems have the merit of having much stronger optomechanical interactions. However, to date, the torsional optomechanical effects of coupled cavities have rarely been investigated. In this Letter, we report a torsional optical spring effect in coupled nanobeam photonic crystal cavities. One of the cavities is suspended by a multi-degree-of-freedom spring mechanism that supports torsional vibration modes. The cavities' light field acts in reverse on the selected torsional mode, thus generating a torsional optical spring effect. The experimental results show that the third-order torsional mode of the spring mechanism is optically stiffened and a maximum frequency increase of 77.1 Hz is obtained. The device provides a novel configuration for the optomechanical design of a new degree of freedom (torsional motion) and the coupled cavities are favorable for strong optomechanical interactions in the torsional direction.
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17
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Li H, Li M. Optomechanical photon shuttling between photonic cavities. NATURE NANOTECHNOLOGY 2014; 9:913-919. [PMID: 25240675 DOI: 10.1038/nnano.2014.200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 08/14/2014] [Indexed: 06/03/2023]
Abstract
Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave mixing between photons and phonons, and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong non-local effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a multicavity optomechanical device in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of this 'photon see-saw', are modulated antisymmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation, which strongly modulates the inter-cavity coupling and shuttles photons to the other empty cavity during every oscillation cycle in a well-regulated fashion.
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Affiliation(s)
- Huan Li
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Mo Li
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Tetienne JP, Hingant T, Kim JV, Diez LH, Adam JP, Garcia K, Roch JF, Rohart S, Thiaville A, Ravelosona D, Jacques V. Nanoscale imaging and control of domain-wall hopping with a nitrogen-vacancy center microscope. Science 2014; 344:1366-9. [DOI: 10.1126/science.1250113] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Manfrini M, Kim JV, Petit-Watelot S, Van Roy W, Lagae L, Chappert C, Devolder T. Propagation of magnetic vortices using nanocontacts as tunable attractors. NATURE NANOTECHNOLOGY 2014; 9:121-125. [PMID: 24336405 DOI: 10.1038/nnano.2013.265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 11/08/2013] [Indexed: 06/03/2023]
Abstract
Magnetic vortices in thin films are in-plane spiral spin configurations with a core in which the magnetization twists out of the film plane. Vortices result from the competition between atomic-scale exchange forces and long-range dipolar interactions. They are often the ground state of magnetic dots, and have applications in medicine, microwave generation and information storage. The compact nature of the vortex core, which is 10-20 nm wide, makes it a suitable probe of magnetism at the nanoscale. However, thus far the positioning of a vortex has been possible only in confined structures, which prevents its transport over large distances. Here we show that vortices can be propagated in an unconstrained system that comprises electrical nanocontacts (NCs). The NCs are used as tunable vortex attractors in a manner that resembles the propelling of space craft with gravitational slingshots. By passing current from the NCs to a ferromagnetic film, circulating magnetic fields are generated, which nucleate the vortex and create a potential well for it. The current becomes spin polarized in the film, and thereby drives the vortex into gyration through spin-transfer torques. The vortex can be guided from one NC to another by tuning attractive strengths of the NCs. We anticipate that NC networks may be used as multiterminal sources of vortices and spin waves (as well as heat, spin and charge flows) to sense the fundamental interactions between physical objects and fluxes of the next-generation spintronic devices.
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Affiliation(s)
- M Manfrini
- 1] IMEC, Kapeldreef 75, B-3001 Leuven, Belgium [2] Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
| | - Joo-Von Kim
- 1] Institut d'Electronique Fondamentale, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8622, 91405 Orsay, France [2] Université Paris-Sud, 91405 Orsay, France
| | - S Petit-Watelot
- 1] Institut d'Electronique Fondamentale, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8622, 91405 Orsay, France [2] Université Paris-Sud, 91405 Orsay, France [3]
| | - W Van Roy
- IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
| | - L Lagae
- 1] IMEC, Kapeldreef 75, B-3001 Leuven, Belgium [2] Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
| | - C Chappert
- 1] Institut d'Electronique Fondamentale, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8622, 91405 Orsay, France [2] Université Paris-Sud, 91405 Orsay, France
| | - T Devolder
- 1] Institut d'Electronique Fondamentale, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8622, 91405 Orsay, France [2] Université Paris-Sud, 91405 Orsay, France
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Sukhostavets OV, Pigeau B, Sangiao S, de Loubens G, Naletov VV, Klein O, Mitsuzuka K, Andrieu S, Montaigne F, Guslienko KY. Probing the anharmonicity of the potential well for a magnetic vortex core in a nanodot. PHYSICAL REVIEW LETTERS 2013; 111:247601. [PMID: 24483698 DOI: 10.1103/physrevlett.111.247601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Indexed: 06/03/2023]
Abstract
The anharmonicity of the potential well confining a magnetic vortex core in a nanodot is measured dynamically with a magnetic resonance force microscope (MRFM). The stray field of the MRFM tip is used to displace the equilibrium core position away from the nanodot center. The anharmonicity is then inferred from the relative frequency shift induced on the eigenfrequency of the vortex core translational mode. An analytical framework is proposed to extract the anharmonic coefficient from this variational approach. Traces of these shifts are recorded while scanning the tip above an isolated nanodot, patterned out of a single crystal FeV film. We observe a +10% increase of the eigenfrequency when the equilibrium position of the vortex core is displaced to about one-third of its radius. This calibrates the tunability of the gyrotropic mode by external magnetic fields.
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Affiliation(s)
- O V Sukhostavets
- Departamento de Física de Materiales, Universidad del Pais Vasco, 20018 San Sebastian, Spain
| | - B Pigeau
- Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - S Sangiao
- Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - G de Loubens
- Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - V V Naletov
- Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France and Institute of Physics, Kazan Federal University, Kazan 420008, Russian Federation
| | - O Klein
- Service de Physique de l'État Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France
| | - K Mitsuzuka
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France
| | - S Andrieu
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France
| | - F Montaigne
- Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54 506 Nancy, France
| | - K Y Guslienko
- Departamento de Física de Materiales, Universidad del Pais Vasco, 20018 San Sebastian, Spain and IKERBASQUE, The Basque Foundation for Science, 48011 Bilbao, Spain
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Bohn F, Corrêa MA, Viegas ADC, Papanikolaou S, Durin G, Sommer RL. Universal properties of magnetization dynamics in polycrystalline ferromagnetic films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:032811. [PMID: 24125316 DOI: 10.1103/physreve.88.032811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Indexed: 06/02/2023]
Abstract
We investigate the scaling behavior in the statistical properties of Barkhausen noise in ferromagnetic films. We apply the statistical treatment usually employed for bulk materials in experimental Barkhausen noise time series measured with the traditional inductive technique in polycrystalline ferromagnetic films having different thickness from 100 to 1000 nm and determine the scaling exponents. Based on this procedure, we group the samples in a single universality class, since the scaling behavior of Barkhausen avalanches is characterized by exponents τ∼1.5, α∼2.0, and 1/σνz∼ϑ∼2.0 for all the films. We interpret these results in terms of theoretical models and provide experimental evidence that a well-known mean-field model for the dynamics of a ferromagnetic domain wall in three-dimensional ferromagnets can be extended for films. We identify that the films present an universal three-dimensional magnetization dynamics, governed by long-range dipolar interactions, even at the smallest thicknesses, indicating that the two-dimensional magnetic behavior commonly verified for films cannot be generalized for all thickness ranges.
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Affiliation(s)
- Felipe Bohn
- Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN, Brazil
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