Increased magnetic damping in ultrathin films of Co2FeAl with perpendicular anisotropy

Y. K. Takahashi; Y. Miura; R. Choi; T. Ohkubo; Z. C. Wen; K. Ishioka; R. Mandal; R. Medapalli; H. Sukegawa; S. Mitani; E. E. Fullerton; K. Hono

doi:10.1063/1.4989379

Increased magnetic damping in ultrathin films of Co₂FeAl with perpendicular anisotropy

Y. K. Takahashi^*, Y. Miura, R. Choi, T. Ohkubo, Z. C. Wen, K. Ishioka, R. Mandal, R. Medapalli, H. Sukegawa, S. Mitani, E. E. Fullerton, K. Hono

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

20 Citations (Scopus)

Abstract

We estimated the magnetic damping constant α of Co₂FeAl (CFA) Heusler alloy films of different thicknesses with an MgO capping layer by means of time-resolved magneto-optical Kerr effect and ferromagnetic resonance measurements. CFA films with thicknesses of 1.2 nm and below exhibited perpendicular magnetic anisotropy arising from the presence of the interface with MgO. While α increased gradually with decreasing CFA film thickness down to 1.2 nm, it was increased substantially when the thickness was reduced further to 1.0 nm. Based on the microstructure analyses and first-principles calculations, we attributed the origin of the large α in the ultrathin CFA film primarily to the Al deficiency in the CFA layer, which caused an increase in the density of states and thereby in the scatterings of their spins.

Original language	English
Article number	252409
Journal	Applied Physics Letters
Volume	110
Issue number	25
DOIs	https://doi.org/10.1063/1.4989379
Publication status	Published - 2017 Jun 19
Externally published	Yes

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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title = "Increased magnetic damping in ultrathin films of Co2FeAl with perpendicular anisotropy",

abstract = "We estimated the magnetic damping constant α of Co2FeAl (CFA) Heusler alloy films of different thicknesses with an MgO capping layer by means of time-resolved magneto-optical Kerr effect and ferromagnetic resonance measurements. CFA films with thicknesses of 1.2 nm and below exhibited perpendicular magnetic anisotropy arising from the presence of the interface with MgO. While α increased gradually with decreasing CFA film thickness down to 1.2 nm, it was increased substantially when the thickness was reduced further to 1.0 nm. Based on the microstructure analyses and first-principles calculations, we attributed the origin of the large α in the ultrathin CFA film primarily to the Al deficiency in the CFA layer, which caused an increase in the density of states and thereby in the scatterings of their spins.",

author = "Takahashi, {Y. K.} and Y. Miura and R. Choi and T. Ohkubo and Wen, {Z. C.} and K. Ishioka and R. Mandal and R. Medapalli and H. Sukegawa and S. Mitani and Fullerton, {E. E.} and K. Hono",

note = "Funding Information: Work at UCSD supported by the National Science Foundation Award DMR No. 1312750. Publisher Copyright: {\textcopyright} 2017 Author(s).",

year = "2017",

month = jun,

day = "19",

doi = "10.1063/1.4989379",

language = "English",

volume = "110",

journal = "Applied Physics Letters",

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T1 - Increased magnetic damping in ultrathin films of Co2FeAl with perpendicular anisotropy

AU - Takahashi, Y. K.

AU - Miura, Y.

AU - Choi, R.

AU - Ohkubo, T.

AU - Wen, Z. C.

AU - Ishioka, K.

AU - Mandal, R.

AU - Medapalli, R.

AU - Sukegawa, H.

AU - Mitani, S.

AU - Fullerton, E. E.

AU - Hono, K.

PY - 2017/6/19

Y1 - 2017/6/19

N2 - We estimated the magnetic damping constant α of Co2FeAl (CFA) Heusler alloy films of different thicknesses with an MgO capping layer by means of time-resolved magneto-optical Kerr effect and ferromagnetic resonance measurements. CFA films with thicknesses of 1.2 nm and below exhibited perpendicular magnetic anisotropy arising from the presence of the interface with MgO. While α increased gradually with decreasing CFA film thickness down to 1.2 nm, it was increased substantially when the thickness was reduced further to 1.0 nm. Based on the microstructure analyses and first-principles calculations, we attributed the origin of the large α in the ultrathin CFA film primarily to the Al deficiency in the CFA layer, which caused an increase in the density of states and thereby in the scatterings of their spins.

AB - We estimated the magnetic damping constant α of Co2FeAl (CFA) Heusler alloy films of different thicknesses with an MgO capping layer by means of time-resolved magneto-optical Kerr effect and ferromagnetic resonance measurements. CFA films with thicknesses of 1.2 nm and below exhibited perpendicular magnetic anisotropy arising from the presence of the interface with MgO. While α increased gradually with decreasing CFA film thickness down to 1.2 nm, it was increased substantially when the thickness was reduced further to 1.0 nm. Based on the microstructure analyses and first-principles calculations, we attributed the origin of the large α in the ultrathin CFA film primarily to the Al deficiency in the CFA layer, which caused an increase in the density of states and thereby in the scatterings of their spins.

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Increased magnetic damping in ultrathin films of Co₂FeAl with perpendicular anisotropy

Abstract

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