Probing the energy barriers in nonuniform magnetization states of circular dots by broadband ferromagnetic resonance

Melkov, G. A.; Kobljanskyj, Yuri; Novosad, V.; Slavin, A. N.; Guslienko, K. Yu.

doi:10.1103/physrevb.88.220407

Cited by 9 publications

(13 citation statements)

References 21 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These materials are important for the emerging fields of magnonics 17 and microwave spintronics.…”

Section: Introductionmentioning

confidence: 99%

Microwave magnetic dynamics in highly conducting magnetic nanostructures

Kostylev

Ding

Ivanov

et al. 2014

Journal of Applied Physics

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We performed low-noise broadband microstrip ferromagnetic resonance (FMR) measurements of the resonant modes of an array of metallic ferromagnetic nanostripes. In addition to a strong signal of the fundamental mode, we observed up to five weak-amplitude peaks in the field-resolved FMR traces, depending on the frequency. These higher-order absorption peaks have been theoretically identified as due to resonant excitation of odd and even standing spin waves across the direction of confinement in array plane (i.e., across the stripe width). The theory we developed suggests that the odd modes become excited in the spatially uniform microwave field of the FMR setup due to the large conductivity of metals. This promotes excitation of large-amplitude eddy currents in the sample by the incident microwave magnetic field and ultimately results in excitation of these modes. Following this theory, we found that the eddy current contribution is present only for patterned materials and when the microwave magnetic field is incident on one surface of sample surface, as it is in the case of a microstrip FMR. V C 2014 AIP Publishing LLC.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These materials are important for the emerging fields of magnonics 17 and microwave spintronics.…”

Section: Introductionmentioning

confidence: 99%

Microwave magnetic dynamics in highly conducting magnetic nanostructures

Kostylev

Ding

Ivanov

et al. 2014

Journal of Applied Physics

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“…To investigate experimentally the microwave absorption in a two-dimensional array of inplane magnetized non-interacting magnetic dots, we used a standard technique of vector network analyzer ferromagnetic resonance (VNA-FMR) [6][7][8][9][10][11][12][13][14], which has been employed previously to investigate the microwave properties of magnetic dot arrays [8,9,[11][12][13][14][15]. The microwave measurements were conducted by the VNA set-up ZVA-8 (Rohde&Schwarz).…”

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confidence: 99%

“…The dots are saturated ( = M M 0 ) at a field above the vortex annihilation field H an . When the bias magnetic field is decreasing and reaches the value below H an (see the upper lobe in the inset of figure 1), the magnetization first decreases slightly, keeping a quasi-uniform ground state in the dot, and then decreases drastically due to the dot transition, first into a deformed C-state (just above the nucleation field H n [15]) and, eventually, to the vortex ground state (just below H n [4]). The vortex state is stable up to = − H H an , when the bias field decreases to negative values.…”

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confidence: 99%

“…Frames (a)-(d) in the left-hand column correspond to the quasi-uniform stable state of the dots (the upper lobe of the hysteresis loop), while frames (e)-(h) in the right-hand column correspond to the vortex stable state (the lower lobe of the hysteresis loop). It is clear from figure 2 that the microwave absorption properties of a dot array in the quasi-uniform and vortex stable states of the dots are qualitatively different because different spin wave modes are excited by the uniform ac magnetic field in magnetic dots existing in these two minimal energy states [4,15].…”

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confidence: 99%

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Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

et al. 2014

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When the in-plane bias magnetic field acting on a flat circular magnetic dot is smaller than the saturation field, there are two stable competing magnetization configurations of the dot: the vortex and the quasi-uniform (C-state). We measured microwave absorption properties in an array of non-interacting permalloy dots in the frequency range 1-8 GHz when the in-plane bias magnetic field was varied in the region of the dot magnetization state bi-stability. We found that the microwave absorption properties in the vortex and quasi-uniform stable states are substantially different, so that switching between these states in a fixed bias field can be used for the development of reconfigurable microwave magnetic materials.

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“…[1][2][3][4][5][6][7][8][9][10][11][12]). These materials are important for the emerging fields of magnonics [13], microwave spintronics [14][15][16][17], and for novel sensor applications [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Microwave magnetic dynamics in ferromagnetic metallic nanostructures lacking inversion symmetry

Kostylev

Yang

Maksymov

et al. 2016

Journal of Applied Physics

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In this work we carried out systematic experimental and theoretical investigations of the ferromagnetic resonance (FMR) response of quasi-twodimensional magnetic nano-objects -microscopically long nanostripes made of ferromagnetic metals. We were interested in the impact of the symmetries of this geometry on the FMR response. Three possible scenarios, from which the inversion symmetry break originated were investigated: (1) from the shape of the stripe crosssection, (2) from the double-layer structure of the stripes with exchange coupling between the layers, and (3) from the single-side incidence of the microwave magnetic field on the plane of the nano-pattern. The latter scenario is characteristic of the stripline FMR configuration. It was found that the combined effect of the three symmetry breaks is much stronger than impacts of each of these symmetry breaks separately. I. IntroductionFerromagnetic resonance (FMR) is a powerful tool for studying dynamic properties of metallic ferromagnetic thin films and nanostructures (see e.g., Refs. [1][2][3][4][5][6][7][8][9][10][11][12]). These materials are important for the emerging fields of magnonics [13], microwave spintronics [14][15][16][17], and for novel sensor applications [18][19][20][21].Macroscopically-long stripes with sub-micron cross-section made of ferromagnetic materials have attracted a lot of attention, because this geometry is a very convenient model object for studying the impact of geometric confinement on magnetization dynamics on the sub-micrometre and nanometer scales [22][23][24][25][26][27][28][29][30]. The main reasons for the attractiveness of this geometry are the practical absence of a static demagnetizing field H ds when the external field is applied along the stripes (i.e. along the axis y in Fig. 1(a)) and the quasi-two-dimensional (2D) character of the dynamics.The former property allows clear separation of the static and dynamic demagnetizing effects. Furthermore, because of the absence of H ds , the static magnetization configuration for the stripes is very simple. The static magnetization vector has the same magnitude -equal to the saturation magnetization for the material -and the same direction -along the stripe -for every point on the stripe crosssection. Due to strong shape anisotropy for this geometry, this configuration remains very stable even at remanence [29][30][31]. The simplicity of the magnetization ground state, together with the 2D character of the magnetization dynamics, results in simple analytical and quasi-analytical theoretical models able to deliver a clear physical

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Probing the energy barriers in nonuniform magnetization states of circular dots by broadband ferromagnetic resonance

Cited by 9 publications

References 21 publications

Microwave magnetic dynamics in highly conducting magnetic nanostructures

Microwave magnetic dynamics in highly conducting magnetic nanostructures

Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

Microwave magnetic dynamics in ferromagnetic metallic nanostructures lacking inversion symmetry

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