Fast spin-wave-mediated magnetic vortex core reversal

Kammerer, Matthias; Stoll, Hermann; Noske, Matthias; Sproll, Markus; Weigand, Markus; Illg, Christian; Woltersdorf, Georg; Fähnle, M.; Back, Christian; Schütz, Gisela

doi:10.1103/physrevb.86.134426

Cited by 50 publications

(43 citation statements)

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“…This behavior has been shown by micromagnetic simulations. 11 In previous investigations on vortex core reversal, the general results were very similar for two-dimensional (2D) 1,2,5,6 and for three-dimensional (3D) 7,11 simulations, showing that the three-dimensionality of the magnetization dynamics has an effect on the details of the reversal mechanism 12 but has only minor influence on whether the core is switched or not. However, in sufficiently thick disks, additional exchange dominated eigenmodes exist.…”

Section: Introductionmentioning

confidence: 73%

“…It has been demonstrated that the vortex core polarity can be dynamically reversed by exciting one of the eigenmodes of the vortex structure, i.e., the gyrotropic mode [1][2][3][4] or dipolar spin-wave modes. [5][6][7] For the vortex gyrotropic mode G 0 , the vortex core performs a translational motion with frequencies in the range of 100 MHz to 1 GHz (depending on the disk dimensions and the material of the disk). 8 Dipolar spin-wave modes have frequencies in the GHz range and describe dynamic excitations of the planar part of the vortex structure.…”

Section: Introductionmentioning

confidence: 99%

“…Unidirectional switching, which is a prerequisite for data storage applications, is possible by using rotating in-plane fields with the frequency and sense of rotation tuned to the gyrotropic eigenmode G 0 , 2 or to azimuthal spin waves. 5 Alternatively, the excitation can consist of short multi-GHz rotating field bursts 6 or can have the shape of two orthogonal monopolar pulses 7 with pulse amplitude B, pulse length s, and a delay Dt ¼ s=2 between the pulses. For the latter type of excitation, switching times shorter than 100 ps were found 7 for pulse amplitudes of a few tens of mT.…”

Section: Introductionmentioning

confidence: 99%

“…Due to their symmetry, dipolar spin-wave modes with azimuthal mode numbers jmj ¼ 1 can be efficiently excited by magnetic in-plane fields. To achieve vortex core reversal, dynamical external magnetic in-plane fields 1,2,[5][6][7]11 or dynamical spin-polarized currents 3 have been used. Unidirectional switching, which is a prerequisite for data storage applications, is possible by using rotating in-plane fields with the frequency and sense of rotation tuned to the gyrotropic eigenmode G 0 , 2 or to azimuthal spin waves.…”

Section: Introductionmentioning

confidence: 99%

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Spin wave mediated unidirectional vortex core reversal by two orthogonal monopolar field pulses: The essential role of three-dimensional magnetization dynamics

Noske

Stoll

Fähnle

et al. 2016

Journal of Applied Physics

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Scanning transmission x-ray microscopy is employed to investigate experimentally the reversal of the magnetic vortex core polarity in cylindrical Ni81Fe19 nanodisks triggered by two orthogonal monopolar magnetic field pulses with peak amplitude B0, pulse length τ=60 ps, and delay time Δt in the range from −400 ps to +400 ps between the two pulses. The two pulses are oriented in-plane in the x- and y-directions. We have experimentally studied vortex core reversal as a function of B0 and Δt. The resulting phase diagram shows large regions of unidirectional vortex core switching where the switching threshold is modulated due to resonant amplification of azimuthal spin waves. The switching behavior changes dramatically depending on whether the first pulse is applied in the x- or the y-direction. This asymmetry can be reproduced by three-dimensional micromagnetic simulations but not by two-dimensional simulations. This behavior demonstrates that in contrast to the previous experiments on vortex core reversal, the three-dimensionality in the dynamics is essential here.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spin wave mediated unidirectional vortex core reversal by two orthogonal monopolar field pulses: The essential role of three-dimensional magnetization dynamics

Noske

Stoll

Fähnle

et al. 2016

Journal of Applied Physics

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“…X-ray microscopy brings new insights to materials researchers from different fields by adding either a 3rd spatial [1,2] or a temporal [3,4] dimension to materials analysis, both at very high resolution. To carry out either scanning or full-field transmission microscopy with X-rays, one has to focus the radiation in some way; yet focusing of especially hard X-rays (HXR), to nano-sized spots, is no easy task.…”

Section: Introductionmentioning

confidence: 99%

Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 12 keV

Keskinbora¹,

Robisch²,

Mayer³

et al. 2014

Opt. Express

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X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (fullpitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV. ©2014 Optical Society of AmericaOCIS codes: (340.7460) X-ray microscopy; (340.0340) X-ray optics; (340.6720) Synchrotron radiation; (340.7480) X-rays, soft x-rays, extreme ultraviolet (EUV); (050.1965) Diffractive lenses; (220.4241) Nanostructure fabrication. References and links1. J. Vila-Comamala, Y. Pan, J. J. Lombardo, W. M. Harris, W. K. S. Chiu, C. David, and Y. Wang, "Zonedoubled Fresnel zone plates for high-resolution hard X-ray full-field transmission microscopy," J. Synchrotron Radiat. 19(5), 705-709 (2012). 2. E. Zschech, C. Wyon, C. E. Murray, and G. Schneider, "Devices, materials, and processes for nanoelectronics: characterization with advanced x-ray techniques using lab-based and synchrotron radiation sources," Adv. Eng. Mater. 13(8), 811-836 (2011 Schütz, "Fast spin-wave-mediated magnetic vortex core reversal," Phys. Rev. B 86(13), 134426 (2012). 5. J. Kirz and C. Jacobsen, "The history and future of X-ray microscopy," J. Phys. Conf. Ser. 186, 012001 (2009). 6. P. Kirkpatrick and A. V. Baez, "Formation of optical images by X-Rays," J. Opt. Soc. Am. 38(9), 766-774 (1948 International Journal of Optics 31(4), 403-413 (1984). 46. A. A. Michelson, Studies in Optics (Dover Publications, Incorporated, 1995. 47. G. R. Morrison, "Phase contrast and darkfield imaging in x-ray microscopy," Proc. SPIE 1741, 186-193 (1993).

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Single‐Step 3D Nanofabrication of Kinoform Optics via Gray‐Scale Focused Ion Beam Lithography for Efficient X‐Ray Focusing

Keskinbora

Grévent

Hirscher

et al. 2015

Advanced Optical Materials

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material is achieved, kinoform lenses exhibit focusing effi ciencies of 100% [ 10 ] and concentrate all the incident light into a single focus. This very desirable property is of crucial importance for many applications such as laboratory based X-ray microscopy where every single photon is important due to limited source brightness. Unfortunately, to date the fabrication of kinoform lenses for X-ray microscopy mainly relies on approximations, which reduce their potential effi ciency. Approximations based on step profi les have been developed including a variety of routes such as optical gray scale lithography, [ 2b,c ] multilevel/multilayer quasi-Kinoforms, [ 11 ] consecutive overlaid e-beam lithographic steps, [ 10 ] direct ion beam writing of steps profi les, [ 12 ] 2D approximations, [ 13 ] and stacking of two binary FZPs. [ 14 ] Recently, progress was made in structuring of continuous linear and circular blazed profi les via combining focused ion beam implantation and reactive ion etching, [ 15 ] and diamond tool based micro-machining [ 16 ] sometimes also in combination with reactive ion etching. [ 17 ] A few attempts toward Fresnel lenses using direct write gray scale ion beam lithography (IBL) were already reported but with rather large feature sizes, small apertures and dedicated mostly to the optical wavelength range, [ 18 ] while infrared applications were also reported. [ 19 ] Overall, the preparation of the fabled circularly symmetric, continuous kinoform 3D surface profi le remains a daunting task especially for X-ray applications and was recently considered impossible with current fabrication methods. [ 14a ] Here, for the fi rst time, we demonstrate a simple and singlestep fabrication strategy for X-ray kinoform lenses approaching the ideal profi le and we show their performance for X-ray microscopy (XRM) supported with imaging and effi ciency measurements in a state of the art X-ray microscope (STXM) located at BESSY II synchrotron radiation facility. [ 20 ] XRM has developed as a powerful analytical tool used in various research fi elds ranging from biology-biochemistry and materials science/engineering to information technology with applications including for instance, imaging of ultracellular structure, [ 21 ] in situ and in operando examination of chemical reactions via spectroscopy and imaging, [ 22 ] and investigation of ultrafast A kinoform lens is a highly effi cient photonic device capable of focusing a wide range of electromagnetic radiation. Unfortunately, its realization without the need of any approximation remained elusive for a very long time. A direct, simple and precise fabrication method was still missing. Here, an effi cient preparation scheme is presented for the fi rst time. Two kinoform lenses made out of polycrystalline gold and nano-crystalline PdSi, are successfully fabricated, thoroughly characterized and tested for their ultimate focusing performances at soft X-ray energies. The fabrication is made possible by means of gray-scale direct-write ion beam lithograph...

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Fast spin-wave-mediated magnetic vortex core reversal

Cited by 50 publications

References 22 publications

Spin wave mediated unidirectional vortex core reversal by two orthogonal monopolar field pulses: The essential role of three-dimensional magnetization dynamics

Spin wave mediated unidirectional vortex core reversal by two orthogonal monopolar field pulses: The essential role of three-dimensional magnetization dynamics

Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 12 keV

Single‐Step 3D Nanofabrication of Kinoform Optics via Gray‐Scale Focused Ion Beam Lithography for Efficient X‐Ray Focusing

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