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Lock, E. H.

doi:10.1070/pu2008v051n04abeh006460

Cited by 52 publications

(33 citation statements)

References 36 publications

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“…Following Refs. [11,24,25], we call a spin-wave "forward" if kv g > 0 and "backward" if kv g < 0. With decreasing spinwave wavelength, the exchange term Dk 2 becomes dominant and the isofrequency curves recover a more circular shape.…”

Section: Spin-wave Power Flowmentioning

confidence: 99%

Electric-field control of spin-wave power flow and caustics in thin magnetic films

2018

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An external electric field can modify the strength of the spin-orbit interaction between spins of ions in magnetic crystals. This influence leads to a spin-wave frequency shift that is linear in both the applied electric field and the wave vector of the spin wave. Here we study theoretically the external electric field as a means of control of the spin-wave power flow in thin ferromagnets. The spin-wave group velocity and focusing patterns are obtained from the slowness (isofrequency) curves by evaluating their curvature at each point of the reciprocal space. We show that the combination of the magnetodipole interaction and the electric field can result in nonreciprocal unidirectional caustic beams of dipole-exchange spin waves. We demonstrate that the degree of asymmetry of the spin-wave power flow can be tuned with the external electric field. Our findings open a novel avenue for spin-wave manipulation and development of electrically tunable magnonic devices.

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Section: Spin-wave Power Flowmentioning

confidence: 99%

Electric-field control of spin-wave power flow and caustics in thin magnetic films

2018

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“…Together with the difference in the incidence and reflection angles, the tilt of the phase fronts suggests the effect of the highly anisotropic dispersion inherent to magnetostatic waves [1,23,[31][32][33][34]. Hence, we interpret our observations in terms of the spatial distributions of the orientations of the magnetization and the value of the internal magnetic field, which determine the local axis and strength of the dispersion's anisotropy.…”

mentioning

confidence: 85%

“…The symmetry axis of the anisotropic magnetostatic dispersion coincides with the direction of the magnetization [21][22][23]. This anisotropic dispersion leads to the formation of nondiffracting caustic spin-wave beams [24][25][26][27][28][29][30] and to anomalous spin-wave reflection, refraction, and diffraction [31][32][33][34][35]. Here, we explore these ideas in networks of magnonic waveguides [6,8,[12][13][14][15][16][17][18][19][20]24,29,36], in which not only the internal magnetic field and the magnetization, but also the associated anisotropic dispersion are nonuniform and contribute significantly to the observed switching of the direction of spin-wave propagation.…”

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confidence: 99%

Towards graded-index magnonics: Steering spin waves in magnonic networks

et al. 2015

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Magnonics explores precessional excitations of ordered spins in magnetic materials-so-called spin wavesand their use as information and signal carriers within networks of magnonic waveguides. Here, we demonstrate that the nonuniformity of the internal magnetic field and magnetization inherent to magnetic structures creates a medium of graded refractive index for propagating magnetostatic waves and can be used to steer their propagation. The character of the nonuniformity can be tuned and potentially programmed using the applied magnetic field, which opens exciting prospects for the field of graded-index magnonics. Over the past decade, magnonics (the study of spin waves-precessional excitations of ordered spins in magnetic materials [1]) has emerged as one of the most rapidly growing research fields in magnetism [2,3]. Moreover, recent advances in the understanding of fundamental properties of spin waves in magnetic micro-and nanostructures have highlighted magnonics as a potential rival of or complement to semiconductor technology in the field of data communication and processing [4]. The push for miniaturization renders ferromagnetic transition metals and their alloys to be materials of choice for the fabrication of spin-wave devices [5,6]. However, loss reduction, the shortening of the wavelength of studied spin waves, and the associated miniaturization of the implemented magnonic concepts and devices remain major challenges in both experimental research and technological development in magnonics [2,3].In this Rapid Communication, we explore an approach to meet these challenges that is based on the concept of gradedindex (or gradient-index) optics [7]. As applied to spin waves, this concept is based on the following basic ideas. First, the propagation of spin waves is controlled using subwavelength, often continuously varying, magnetic nonuniformities [8,9]. This should minimize scaling of the device size with the magnonic wavelength, in contrast to, e.g., magnonic crystal based approaches [3], and thereby ease the associated patterning resolution requirements. Indeed, nonuniform effective magnetic field and magnetization configurations have been shown to confine [10,11] and channel [12][13][14][15] spin waves, to continuously modify their character [16][17][18], and to enable their coupling to essentially uniform free space microwaves [19,20]. Here, we go further by exploiting in addition the anisotropic dispersion inherent to spin waves dominated by the dynamic magneto-dipole field-so-called magnetostatic spin waves [1]. The symmetry axis of the anisotropic magnetostatic dispersion coincides with the direction of the magnetization [21][22][23]. This anisotropic dispersion leads to the formation of nondiffracting caustic spin-wave beams * Corresponding author: v.v.kruglyak@exeter.ac.uk [24][25][26][27][28][29][30] and to anomalous spin-wave reflection, refraction, and diffraction [31][32][33][34][35]. Here, we explore these ideas in networks of magnonic waveguides [6,8,[12][13][14][15][16][17][18][19][20]24,...

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“…The magnitude of the energy sent in that direction is proportional to the square root of the curvature of the surface at a given point. When the curvature is zero, one finds the so-called caustics beams, when for waves having different wave vectors k the group velocity is the same and, formally, in those directions the power flow diverges [8][9][10][11].…”

Section: Propagation Of Spin Waves Under An Electric Fieldmentioning

confidence: 99%

“…In anisotropic medium, the group velocity v g and wave vector k are noncollinear, in general. In this case, a situation is possible when the energy transferred to anisotropic medium from a point excitation source transfers away not in circular waves but in focused directions, forming so-called caustic wave beams [8,9]. The focusing direction can be found from the isofrequency curves (curves of constant ω in k-space) by calculating the normal to the curve (the group velocity, v g fωpk, Eq{fkq at each point.…”

Section: Propagation Of Spin Waves Under An Electric Fieldmentioning

confidence: 99%

Electric Field Control of Magnon Power Flow in Thin Ferromagnet Films

Krivoruchko

Savchenko

2018

Acta Phys. Pol. A

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External electric field can modify the strength of the spin-orbit interaction between spins of ions in magnetic crystals. This influence leads to a spin wave frequency shift that is linear in both the applied electric field and the wave vector of the spin wave. Here, we explore theoretically the external electric field as a means of control of the spin wave power flow in ultrathin ferromagnets. The spin wave group velocity and focusing pattern is obtained from the slowness (isofrequency) curves by evaluating their curvature at each point of the reciprocal space. We show that the combination of the magneto-dipole interaction and the electric field can result in non-reciprocal unidirectional caustic beams of dipole-exchange spin waves. Our findings open a novel avenue for spin wave manipulation and development of electrically tuneable magnonic devices.

show abstract

Untitled

Cited by 52 publications

References 36 publications

Electric-field control of spin-wave power flow and caustics in thin magnetic films

Electric-field control of spin-wave power flow and caustics in thin magnetic films

Towards graded-index magnonics: Steering spin waves in magnonic networks

Electric Field Control of Magnon Power Flow in Thin Ferromagnet Films

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