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Switching magnetic vortex core by a single nanosecond current pulse

Keisuke Yamada, Shinya Kasai, Yoshinobu Nakatani, Kensuke Kobayashi, Teruo Ono
2008 Applied Physics Letters  
In a ferromagnetic nanodisk, the magnetization tends to swirl around in the plane of the disk and can point either up or down at the center of this magnetic vortex.  ...  This method also provides the precise control of the core direction, which constitutes fundamental technology for realizing a vortex core memory.  ...  The experimentally obtained critical current density for the switching is smaller than the value in the Figure 1 1 shows an atomic force microscope image of the sample and the schematic configuration  ... 
doi:10.1063/1.3001588 fatcat:lwfi4nq2bfhmzotsgl56phcgau

Probing the Spin Polarization of Current by Soft X-Ray Imaging of Current-Induced Magnetic Vortex Dynamics

Shinya Kasai, Peter Fischer, Mi-Young Im, Keisuke Yamada, Yoshinobu Nakatani, Kensuke Kobayashi, Hiroshi Kohno, Teruo Ono
2008 Physical Review Letters  
Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micronsized Permalloy disk.  ...  The result also provides the spin polarization of the current to be 0.67 +/-0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.  ...  We have performed time-resolved magnetic transmission soft X-ray microscopy (M-TXM) [21, 22] to obtain real-time and real-space imaging of the current-induced translational motion of the vortex core  ... 
doi:10.1103/physrevlett.101.237203 pmid:19113588 fatcat:lfyu7gtah5btxnq77stqf2qlzi

Toroidal metamaterials: Transition from 3D concept to 2D flatland

Manoj Gupta, Ranjan Singh
2020 Reviews in Physics  
Toroidal dipole, which is described as poloidal currents flowing on the surface of torus, belongs to a new class of electromagnetic excitation different from electric and magnetic dipoles.  ...  We further discuss the destructive interference between electric and toroidal dipoles to realize nonradiating modes in form of anapole excitation that fulfills the requirement for the excitation of extremely  ...  Acknowledgement The authors acknowledge the funding support from the Ministry of Education Academic Research Fund Tier 1, Grant RG191/17. No new data were created as part of this review.  ... 
doi:10.1016/j.revip.2020.100040 fatcat:fevej5g63vddxcypdbc7u2hly4

Manipulation and coherence of ultra-cold atoms on a superconducting atom chip

Simon Bernon, Helge Hattermann, Daniel Bothner, Martin Knufinke, Patrizia Weiss, Florian Jessen, Daniel Cano, Matthias Kemmler, Reinhold Kleiner, Dieter Koelle, József Fortágh
2013 Nature Communications  
We load atoms into a persistent-current trap engineered in the vicinity of an off-resonance coplanar resonator, and observe that the coherence of hyperfine ground states is preserved for several seconds  ...  In our experiment, we characterize the coherence of superposition states of 87Rb atoms magnetically trapped on a superconducting atom-chip.  ...  This experimentally realized trap is simulated in Fig. 2(c) where both the resulting potential and the current densities are depicted.  ... 
doi:10.1038/ncomms3380 pmid:23986123 fatcat:so7k2c4covgsvbmbtwumvckfsu

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

Kazuhiro Kajikawa, Kazuo Funaki
2011 Superconductors Science and Technology  
This method helps in realizing a magnet system with high-temperature superconducting tapes for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) applications.  ...  Application of an external AC magnetic field parallel to superconducting tapes helps in eliminating the magnetization caused by the shielding current induced in the flat faces of the tapes.  ...  Introduction Superconducting magnets used in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) require a highly uniform magnetic field at their centre.  ... 
doi:10.1088/0953-2048/24/12/125005 fatcat:kktf5jf2gvatti3s7xv54igxou

Magnetic Imaging in Photonic Crystal Microcavities

Silvia Vignolini, Francesca Intonti, Francesco Riboli, Laurent Balet, Lianhe H. Li, Marco Francardi, Annamaria Gerardino, Andrea Fiore, Diederik S. Wiersma, Massimo Gurioli
2010 Physical Review Letters  
Tuning of the magnetic response via the realization of (nanostructured) metamaterials [4] [5] [6] is currently being investigated for the possible realization of perfect lenses and optical cloaking  ...  , where an electric current may be induced via the Faraday-Newmann law.  ... 
doi:10.1103/physrevlett.105.123902 pmid:20867641 fatcat:fjbirhruvbfzvlgbu6j6sz6xne

Boosting magnetic resonance imaging signal-to-noise ratio using magnetic metamaterials

Guangwu Duan, Xiaoguang Zhao, Stephan William Anderson, Xin Zhang
2019 Communications Physics  
Magnetic resonance imaging (MRI) represents a mainstay among the diagnostic imaging tools in modern healthcare.  ...  While promising, the reported applications of metamaterials to MRI remain impractical and fail to realize the full potential of these unique materials.  ...  Acknowledgments: This research was supported by the National Institute of Health (NIH) of Biomedical Imaging and Bioengineering grant 1R21EB024673.  ... 
doi:10.1038/s42005-019-0135-7 pmid:31673637 pmcid:PMC6822984 fatcat:xcs3ki3trrcvpgtyhow2oeyrr4

Subwavelength optical localization with toroidal excitations in plasmonic and Mie metamaterials

Ruisheng Yang, Jing Xu, Nian‐Hai Shen, Fuli Zhang, Quanhong Fu, Junjie Li, Hongqiang Li, Yuancheng Fan
2021 InfoMat  
This review summarizes the development in realizing subwavelength optical localization by exciting toroidal mode in photonic metamaterials.  ...  The toroidal excitations in plasmonic metamaterials and Mie resonant metamaterials, in 3D structures and planar metamaterials, with single or few layers in spectral regime from microwave to optical frequencies  ...  ), whereas magnetic multipoles are created by the closed circulation of electric current (oscillating current density).  ... 
doi:10.1002/inf2.12174 fatcat:e75ymxrtyneexbea6x7pnqf2gm

Electron impact investigation of hybridization schemes in coupled split-ring resonators

Qiuqun Liang, Yuren Wen, Thomas Reindl, Nahid Talebi, Peter A. van Aken
2015 Microscopy and Microanalysis  
The concomitant induction of electric and magnetic moments in SRRs is utilized to realize negative refractive index metamaterials [1] .  ...  We present a comprehensive experimental and theoretical investigation of the plasmon hybridization of coupled Au split-ring resonators (SRRs) by means of electron energy-loss spectroscopy (EELS), energyfiltered  ...  Figure 1 . 1 (a) Calculated EELS maps and (b) experimental EFTEM image of the isolated Au SRR structure and a coupled Au SRRs structure at resonance energies of the fundamental, second-and thirdorder plasmonic  ... 
doi:10.1017/s1431927615012696 fatcat:cppwtepedzebplu7wfskfbaz7u

High-Efficiency Ultra-Violet Dielectric Meta-Holograms with Antiferromagnetic Resonances [article]

Kun Huang, Jie Deng, Hai Sheng Leong, Sherry Lee Koon Yap, Ren Bin Yang, Jinghua Teng, Hong Liu
2018 arXiv   pre-print
We reveal that the induced antiferromagnetic modes maintain one component (e.g., Ex-component) of incident light through even-numbered antiparallel magnetic dipoles (AMDs) but reverse the other component  ...  resonances.  ...  Thus, its current density could be expressed as ( , ) = ( ) − , (S1) where w is the time frequency of light and J(x) is the vectorial current density without the time dependence.  ... 
arXiv:1806.03131v1 fatcat:tvr7gmx5dbe75ov4srfacygrsm

Composite metamaterials with dual-band magnetic resonances in the terahertz frequency regime

Ming Li, Zhenchao Wen, Jinxin Fu, Xu Fang, Yaomin Dai, Rongjuan Liu, Xiufeng Han, Xianggang Qiu
2009 Journal of Physics D: Applied Physics  
The numerical simulations agree well with the experimental results and further clarify the nature of the dual-band magnetic resonances.  ...  Dual-band magnetic resonances, namely, a LC resonance at 4.40 THz and an additional magnetic resonance at 8.64 THz originating from the antiparallel current in wire pairs in the CMMs are observed when  ...  Both magnetic resonances at 8.64 THz and 8.59 THz originate from antiparallel currents induced by external E-field in the corresponding wire pairs.  ... 
doi:10.1088/0022-3727/42/11/115420 fatcat:obnq75tejbbgfkxeplmomcnihy

Tunable Triple-band Terahertz Absorber Based on Bulk-Dirac-Semimetal Metasurface

Jiao Wang, Wan Xinguo, Yan-nan Jiang
2021 IEEE Photonics Journal  
The tunability of the resonant frequencies depends on various Fermi levels.  ...  And the electric or magnetic resonances result in the incident plane waves at different frequencies to be effectively absorbed by the BDS film, which leads to the high absorption at 1.56 THz, 3.28THz,  ...  And the physical origin of the absorption is illustrated by electric/magnetic resonances and power flow/loss density.  ... 
doi:10.1109/jphot.2021.3088868 fatcat:tysjusy5gbfb5blw4xqb2zkv24

Magnetoacoustic tomography with current injection

GuoQiang Liu, Xin Huang, Hui Xia, ShiZeng Wu
2013 Chinese Science Bulletin  
Experimental setup and methods are introduced, and the acoustic signals and the image of a metal object by means of MAT-CI are presented.  ...  In addition, magnetoacoustic tomography is a new nondestructive functional imaging technology, with which we can realize the early diagnosis of human diseases.  ...  The time-varying magnetic field induces an eddy current in the sample or a time-varying current is injected into the sample directly.  ... 
doi:10.1007/s11434-013-5964-2 fatcat:oyams6eytrf7jmgwe5fz3762xi

Controlled Coupling of Spin-Resolved Quantum Hall Edge States

Biswajit Karmakar, Davide Venturelli, Luca Chirolli, Fabio Taddei, Vittorio Giovannetti, Rosario Fazio, Stefano Roddaro, Giorgio Biasiol, Lucia Sorba, Vittorio Pellegrini, Fabio Beltram
2011 Physical Review Letters  
This result may open the way to the realization of scalable quantum-information architectures exploiting the spin degree of freedom of topologically-protected states.  ...  The scheme exploits a spatially-periodic in-plane magnetic field that is created by an array of Cobalt nano-magnets placed at the boundary of the 2DEG.  ...  The field induces charge transfer between the spin up Ψ ↑ SRES (red line) and spin down Ψ ↓ SRES (blue line). b) Density plot of the modulus B in the proximity of the magnetic fingers on the 2DEG plane  ... 
doi:10.1103/physrevlett.107.236804 pmid:22182116 fatcat:ih4nx74xdzedrezqmoqagebyfe

Proposal for an active electromagnetic metamaterial based on spin-torque oscillators

Gen Tatara, Hiroaki T. Ueda, Katsuhisa Taguchi, Yuta Sasaki, Miyuki Nishijima, Akihito Takeuchi
2013 Physical Review B  
We show that close to a resonance with current-driven magnetization, the imaginary part of magnetic permeability becomes indeed negative for either of the two circular polarizations, resulting in negative  ...  The origin of the amplification is the energy supplied to the magnetization by the injected current.  ...  A possibility to lower electric resonance was given by Pendry by use of split ring resonators, where induced currents in rings result in magnetic resonance [8] , and experimental realization of negative  ... 
doi:10.1103/physrevb.87.155102 fatcat:v6powxevqvhrvkee2cxxlsnsda
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