Low damping constant for Co2FeAl Heusler alloy films and its correlation with density of states
TL;DR: Gilbert damping for epitaxial Co2FeAl Heusler alloy films was investigated by analyzing the data of ferromagnetic resonance measured at the frequency of 2.20 GHz as discussed by the authors.
Abstract: Gilbert damping for the epitaxial Co2FeAl Heusler alloy films was investigated. Gilbert damping constant for the films was evaluated by analyzing the data of ferromagnetic resonance measured at the frequency of 2–20 GHz. Gilbert damping constant for the film without annealing was rather large, while it decreased remarkably with postannealing. Gilbert damping constant for the film annealed at 600 °C was ≃0.001. These behavior of Gilbert damping constant can be well explained by the fact that the density of states calculated from first principles decreases with increasing the degree of B2 order.
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Cites background from "Low damping constant for Co2FeAl He..."
...However, materials with only low Z elements often have low spin–orbit coupling and low damping, such as Co2FeAl [66] or CoFeB, in which damping can be as low as α = 0....
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TL;DR: In this article, a unique feature of the band structure has been exploited to achieve similar levels of magnetic damping in a metallic alloy, which is important for a range of applications but is typically insulating.
Abstract: Materials with low magnetic damping are important for a range of applications but are typically insulating, which limits their use. Thanks to a unique feature of the band structure, similar levels of damping can now be achieved in a metallic alloy.
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TL;DR: First-principles calculations well describe both low α and large K(u) for these alloys, and the damping constant α, characterizing macroscopic spin relaxation and being a key factor in spin-transfer-torque systems, is not larger than 0.008 for the δ=1.46 (0.88) film.
Abstract: Spin precession with frequencies up to 280 GHz is observed in Mn(3-δ)Ga alloy films with a perpendicular magnetic anisotropy constant K(u)∼15 M erg/cm(3). The damping constant α, characterizing macroscopic spin relaxation and being a key factor in spin-transfer-torque systems, is not larger than 0.008 (0.015) for the δ=1.46 (0.88) film. Those are about one-tenth of α values for known materials with large K(u). First-principles calculations well describe both low α and large K(u) for these alloys.
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TL;DR: In this paper, a new mechanism was proposed for exciting the magnetic state of a ferromagnet, where a transfer of vectorial spin accompanied an electric current flowing perpendicular to two parallel magnetic films connected by a normal metallic spacer.
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TL;DR: In this paper, a reformulation of the phenomenological theory of the magnetization field was proposed to take large non-eddy-current damping into account in thin Permalloy sheets.
Abstract: In 1955, a phenomenological theory of ferromagnetism was well established and had been corroborated by a considerable amount of experimental data. However, there were problems in the phenomenological theory of the dynamics of the magnetization field. The Landau-Lifshitz equation for damping of the motion of the magnetization field could not account for the large noneddy-current damping in thin Permalloy sheets. The problem undertaken herein is a reformulation of the theory in a way that is more consistent with the theory of damping in other physical systems in order to be able to take large damping into account.
2,181 citations
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