Magnetic Annealing

Slonczewski, J. C.

doi:10.1016/b978-0-12-575301-2.50012-2

Cited by 30 publications

(22 citation statements)

References 47 publications

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“…1a) have been well studied qualitatively [13,14]. Using the integrated equations for the DW dynamics [15,16], it was found that 2 regimes exist. At low current, the spin transfer torque is balanced by an internal restoring torque.…”

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Micromagnetic understanding of current-driven domain wall motion in patterned nanowires

et al. 2005

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In order to explain recent experiments reporting a motion of magnetic domain walls (DW) in nanowires carrying a current, we propose a modification of the spin transfer torque term in the Landau-Lifchitz-Gilbert equation. We show that it explains, with reasonable parameters, the measured DW velocities as well as the variation of DW propagation field under current. We also introduce coercivity by considering rough wires. This leads to a finite DW propagation field and finite threshold current for DW propagation, hence we conclude that threshold currents are extrinsic. Some possible models that support this new term are discussed.Recent research on magnetic nanostructures has shown that effects caused by an electric current flowing across a nanostructure may dominate over the effects due to the field generated by the same current [1,2]. Most of the work up to now, experimental and theoretical, has been devoted to the 3-layer geometry (2 magnetic layers separated by a normal metal spacer, with lateral dimensions well below the micrometer so as to get single domain behaviour). Under current, generation of spin waves [3], layer switching [2] and precession of magnetization [4] have been observed. All these results could be qualitatively explained by the spin transfer model [1]. On the other hand, the situation with an infinite number of layers, namely a magnetic nanowire containing a magnetic domain wall (DW), has just started to be studied. Here, under the sole action of a current, the DW may be moved along the wire, as confirmed by several experiments [5][6][7][8][9][10]. The situation is however more complex than with 3 layers, as the evolution of the current spin polarization across the DW has to be described, so that a deep connection with the problem of DW magnetoresistance exists. Two limits have been identified by the theories, namely the thin and thick DW cases. The length to which the DW width has to be compared is, depending on the model, the spin diffusion length [11], the Larmor precession length [12], or the Fermi wavelength [13]. These lengths are below or of the order of a nanometer in usual ferromagnetic metals. In the experiments cited above (nanowires of typical width 100 nm and thickness 10 nm), the DW width is of the order of 100 nm, much c EDP Sciences * * * AT acknowledges fruitful discussions with F. Piéchon and N. Vernier.

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“…In the case of pure spin transfer the LLG equation could be derived from a least action principle, allowing an easy derivation of the equations [18]. This is no longer true with the additional term and the original procedure must be applied [15,16]. For a one-dimensional TW profile, characterized by a DW width parameter ∆, one then (Fig.…”

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Micromagnetic understanding of current-driven domain wall motion in patterned nanowires

et al. 2005

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“…The macroscopic shape anisotropy of the thin film causes the magnetization to lie in the film plane. The observed field-induced anisotropy during deposition in the presence of applied magnetic field is most likely a result of the alignment of local atomic-pair ordering in the amorphous matrix [7]. It is also possible that some anisotropy in the stress or magnetostriction may be caused by the local atomic pairing.…”

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confidence: 97%

Effect of post-annealing on ultra-high frequency properties of amorphous Fe-Co-B thin films

Chen

Shih

Ellis³

et al. 2000

IEEE Trans. Magn.

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In this paper, FeCoB amorphous thin films were deposited on glass substrates using a triode sputtering source under a uniform applied magnetic field. The as-deposited films exhibit a low coercivity of 1.7 Oe, a high anisotropy field of 37 Oe and 4 17.5 kG, when sputtered with a bias voltage of 180 V. The large anisotropy fields and saturations in these films result in a ferromagnetic resonance frequency as high as 2.63 GHz, a relative permeability of 400-500 and a low dissipation of 10-30 in the frequency range of 0.1-1 GHz. Upon subsequent annealing at 200-400 C for 2 hrs, the magnetic properties of the films are found to be affected significantly. The magnetic properties of the as-deposited and the annealed films have been compared with a considering of the microstructure modification during annealing.Index Terms-UHF properties, soft magnetic properties, amorphous magnetic thin films, Fe-Co-B alloys.

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“…This uniaxial anisotropy results from local atomic-pair ordering in the amorphous matrix. 21 At pressures above 8 ϫ 10 −3 mbar, the anisotropy direction starts deviating from the plasma confining field direction and turns perpendicular at about 14ϫ 10 −3 mbar, as shown in Fig. 5 at a −2 kV target potential.…”

Section: B Magnetic Propertiesmentioning

confidence: 99%

Stress and magnetoelastic properties control of amorphous Fe80B20 thin films during sputtering deposition

Fernández-Martínez

Costa‐Krämer

Briones

2008

Journal of Applied Physics

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In situ stress measurements during sputtering deposition of amorphous Fe 80 B 20 films are used to control their stress and magnetoelastic properties. The substrate curvature induced by the deposited film is measured optically during growth and quantitatively related to the deposition induced accumulated stress. The resulting magnetic properties are later correlated with the measured stress for a wide range of sputtering pressures ͓͑2−25͒ ϫ 10 −3 mbar͔. A significant tensile stress develops at the film-substrate interface during the early growth stages ͑initial 2-3 nm͒. At a critical thickness, a transition is observed from tensile to compressive stress, which is associated with amorphous island coalescence. By further increasing the thickness, a compressive stress follows, which is related to the local distortion induced by the ion peening effect. The Monte Carlo simulations of the sputtering process describe quantitatively the experimental results as a function of the Ar pressure and target bias voltage.

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Magnetic Annealing

Cited by 30 publications

References 47 publications

Micromagnetic understanding of current-driven domain wall motion in patterned nanowires

Micromagnetic understanding of current-driven domain wall motion in patterned nanowires

Effect of post-annealing on ultra-high frequency properties of amorphous Fe-Co-B thin films

Stress and magnetoelastic properties control of amorphous Fe80B20 thin films during sputtering deposition

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