Effective anisotropy of thin nanomagnets: Beyond the surface-anisotropy approach

Caputo, Jean-Guy; Gaididei, Yuri; Kravchuk, Volodymyr P.; Mertens, Franz G.; Sheka, Denis D.

doi:10.1103/physrevb.76.174428

Cited by 17 publications

(16 citation statements)

References 30 publications

(65 reference statements)

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“…For thin nanodots the easy-plane anisotropy parameter A (r) is negative being practically a constant. The in-plane anisotropy parameter B(r) is coordinate-dependent: it vanishes in the disk center and it is sharply localized near the disk edge [20]. One can see that for the easy-plane uniform state nanodot with φ = const, θ = π/2, the second (in-plane) energy term in (1) vanishes after integration and makes no important contribution.…”

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confidence: 84%

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Controlled vortex core switching in a magnetic nanodisk by a rotating field

Kravchuk

Sheka

Gaididei

et al. 2007

Journal of Applied Physics

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The control of the vortex state magnetic nanoparticle by ultrafast magnetic fields is studied theoretically. Using the micromagnetic simulations for the Permalloy nanodisk we demonstrate that the vortex core magnetization can be irreversible switched by the alternating field, rotating in the disk plane, with the frequency about 10 GHz and intensity about 20 mT. We propose an analytical picture of such phenomena involving the creation and annihilation of vortex-antivortex pairs and calculate the phase diagram of the fields parameters leading to the switching.

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confidence: 84%

“…Probably the simplest way which gives physical insight how the dipolar interaction secures the stability of curling ground state is to use a local approach [20]. In this approach the dipolar interaction can be reduced approximately to an on-site anisotropy energy which in the case of a cylindrical nanodot has the form…”

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confidence: 99%

Controlled vortex core switching in a magnetic nanodisk by a rotating field

Kravchuk

Sheka

Gaididei

et al. 2007

Journal of Applied Physics

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“…This corresponds to the exchange length ℓ = $\sqrt{A/4\pi M_S^2}$ ≈ 5.3 nm; the mash size is 2 nm. The second type is original spin–lattice SLASI simulator 55, based on discrete LLG equations (2) for the lattice spins, where the 3D spin distribution is supposed to be independent on z coordinate. Comparison of different approaches is plotted on Figure 1.…”

Section: Magnetic Vortex In the Nanodiskmentioning

confidence: 99%

Magnetic vortex dynamics induced by an electrical current

Gaididei¹,

Kravchuk²,

Sheka³

2009

Int J of Quantum Chemistry

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ABSTRACT:A magnetic nanoparticle in a vortex state is a promising candidate for the information storage. One bit of information corresponds to the upward or downward magnetization of the vortex core (vortex polarity). The dynamics of the magnetic vortex driven by a spin current is studied theoretically. Using a simple analytical model and numerical simulations, we show that a nondecaying vortex motion can be excited by a dc spin-polarized current, whose intensity exceeds a first threshold value as a result of the balance between a spin-torque pumping and damping forces. The irreversible switching of the vortex polarity takes place for a current above a second threshold. The mechanism of the switching, which involves the process of creation and annihilation of a vortex-antivortex pair is described analytically, using a rigid model, and confirmed by detailed spin-lattice simulations.

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“…in the vortex, configuration [5]. Similarity between the effects of the stray field and the surface anisotropy is not casual: Effective surface anisotropy in thin nanomagnets is known to be induced by the dipolar interaction [8,9].…”

Section: Introductionmentioning

confidence: 99%