Voltage controlled modification of flux closure domains in planar magnetic structures for microwave applications

Parkes, D. E.; Beardsley, R.; Bowe, S.; Isakov, Ivan; Warburton, Paul A.; Edmonds, K. W.; Campion, R. P.; Gallagher, B. L.; Rushforth, A. W.; Cavill, S. A.

doi:10.1063/1.4892942

Cited by 13 publications

(15 citation statements)

References 14 publications

(17 reference statements)

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“…Magnetization dynamics in general can be stimulated in a number of ways including using time-varying magnetic fields [3], femtosecond laser excitation [6,7], spin injection [8], and even electric fields [9] or strain [10,11]. The latter examples have received renewed attention in response to the renaissance in magnetoelectric multiferroics [12].…”

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confidence: 99%

“…In these studies of composite magnetoelectrics, a voltage induced strain, from a piezoelectric (PE) or ferroelectric substrate, acts as an additional uniaxial anisotropy, modifying the magnetic free energy and allowing reorientation of the magnetic easy axis. The application of voltage-induced strain to these materials has also been shown to significantly tune the high frequency precessional motion of ferromagnetic resonance (FMR) in both thin films [16] and planar microstructures displaying a uniform magnetization and vortex core [10], respectively. While the study of static strain-induced modification of magnetic domain patterns has received considerable attention, the interaction of a dynamic strain with magnetism in thin films and microstructures has lagged behind.…”

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confidence: 99%

“…For efficient generation of the ground state vortex configuration we have used the OOMMF simulation package [29] to generate the vortex core structure, which has a diameter of ≈7 nm. The vortex core configuration is read into our Landau-Lifshitz-Bloch program and driven via the straininduced anisotropy in the megahertz regime, at the core gyrotropic frequency [10], to excite the oscillations of the 067202-2 core state around its equilibrium. The first point to note here is that the excitation of the magnetization dynamics via a time-dependent strain-induced anisotropy has some key differences with the time-varying applied field case.…”

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Strain Induced Vortex Core Switching in Planar Magnetostrictive Nanostructures

et al. 2015

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The dynamics of magnetic vortex cores is of great interest because the gyrotropic mode has applications in spin torque driven magnetic microwave oscillators, and also provides a means to flip the direction of the core for use in magnetic storage devices. Here, we propose a new means of stimulating magnetization reversal of the vortex core by applying a time-varying strain gradient to planar structures of the magnetostrictive material Fe(81)Ga(19) (Galfenol), coupled to an underlying piezoelectric layer. Using micromagnetic simulations we have shown that the vortex core state can be deterministically reversed by electric field control of the time-dependent strain-induced anisotropy.

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Strain Induced Vortex Core Switching in Planar Magnetostrictive Nanostructures

et al. 2015

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“…X-rays with an energy corresponding to the L 3 absorption edge of Fe were used to acquire images of the in-plane magnetization, using x-ray magnetic circular dichroism (XMCD) as the contrast mechanism. 30 The spatial resolution of the XPEEM used for this study was ~50 nm, in a geometry that allowed the projection of the in-plane component of the magnetization onto the x-ray wavevector to be imaged.…”

Section: Experiments and Sample Detailsmentioning

confidence: 99%

Observation of vortex dynamics in arrays of nanomagnets

Keatley

Gangmei

et al. 2015

Phys. Rev. B

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Vortex dynamics within arrays of square ferromagnetic nano-elements have been studied by time-resolved scanning Kerr microscopy (TRSKM), while x-ray photoemission electron microscopy has been used to investigate their equilibrium state. An alternating field demagnetization process was found to initialize a distribution of equilibrium states within the individual elements of the array, including quasi-uniform states and vortex states of different chirality and core polarization.Repeated initialization revealed some evidence of stochastic behaviour during the formation of the equilibrium state. TRSKM with a spatial resolution of ~300 nm was used to detect vortex gyration within arrays of square nano-elements of 250 nm lateral size. Two arrays were studied consisting of a 9×9 and 5×5 arrangement of nano-elements with 50 nm and 500 nm element edge-to-edge separation to encourage strong and negligible dipolar interactions respectively. In the 5×5 element array, TRSKM images, acquired at a fixed phase of the driving microwave magnetic field, revealed differences in the gyrotropic phase within individual elements. While some phase variation is attributed to the dispersion in the size and shape of elements, the vortex chirality and core polarization are also shown to influence the phase. In the 9×9 array, strong magneto-optical response due to vortex gyration was observed across regions with length equal to either one or two elements.Micromagnetic simulations performed for 2×2 arrays of elements suggest that particular combinations of vortex chirality and polarization in neighbouring elements are required to generate the observed magneto-optical contrast.

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“…Several reports showed vortex reversal by homogeneous strain effect but it is uncontrollable duo to involved randomness during the ferroelectric domain switching [26], and deterministic vortex domain wall control by electric field inside onion-state of magnetic ring [27]. So the sym-metry of single vortex circulation cannot be easily broken deterministically, but the magnetic domain is significantly sensitive (grows or shrinks) to the static strain [28,29]. Previous studies demonstrate that varying fields [9,11,30] are the key factor to trigger the broken vortex symmetry.…”

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confidence: 99%

Deterministic reversal of single magnetic vortex circulation by an electric field

et al. 2020

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The ability to control magnetic vortex is critical for their potential applications in spintronic devices. Traditional methods including magnetic field, spin-polarized current etc. have been used to flip the core and/or reverse circulation of vortex. However, it is challenging for deterministic electric-field control of the single magnetic vortex textures with time-reversal broken symmetry and no planar magnetic anisotropy. Here it is reported that a deterministic reversal of single magnetic vortex circulation can be driven back and forth by a space-varying strain in multiferroic heterostructures, which is controlled by using a bi-axial pulsed electric field. Phase-field simulation reveals the mechanism of the emerging magnetoelastic energy with the space variation and visualizes the reversal pathway of the vortex. This deterministic electric-field control of the single magnetic vortex textures demonstrates a new approach to integrate the low-dimensional spin texture into the magnetoelectric thin film devices with low energy consumption.

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Voltage controlled modification of flux closure domains in planar magnetic structures for microwave applications

Cited by 13 publications

References 14 publications

Strain Induced Vortex Core Switching in Planar Magnetostrictive Nanostructures

Strain Induced Vortex Core Switching in Planar Magnetostrictive Nanostructures

Observation of vortex dynamics in arrays of nanomagnets

Deterministic reversal of single magnetic vortex circulation by an electric field

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