TY - JOUR
T1 - TEM observations of magnetic domains and grain boundaries on spin-sprayed ferrite films exhibiting high permeability usable for gigahertz noise suppressors
AU - Yoshikawa, Hideyuki
AU - Kondo, Koichi
AU - Yoshida, Shigeyoshi
AU - Shindo, Daisuke
AU - Abe, Masanori
PY - 2007/7
Y1 - 2007/7
N2 - Lorentz TEM observations of magnetic domain wall motion, as well as TEM observations of grain boundaries, were performed on spin-sprayed ferrite films #1 (Ni0.17Zn0.22Fe2.61O4) and #2 (Ni0.19Zn0.20Co0.03Fe2.58O 4), both 0.5 μm in thickness. They exhibit much higher natural resonance frequencies than the bulk ferrite and thus have been applied to gigahertz noise suppressors. Films #1 and #2 exhibit prominent and weak in-plane uniaxial magnetic anisotropy, respectively, which is induced along the liquid flow direction during spin-spraying. Both films have columnar crystallites with 100-200 nm widths aligned perpendicular to the film plane, and the boundaries of the crystallites have no pores or impurity phases. Therefore, the crystallites are magnetically exchange-coupled, which is responsible for the unusually high permeability and high natural resonance frequencies of the films. Under zero bias magnetic field, film #1 exhibits mosaic-shaped magnetic domains, whereas film #2 exhibits magnetic domains elongated along the easy magnetization axis, both several hundred nanometers in width. For both films the domain structure remains unchanged when an in-plane bias DC magnetic field, Hdc, of up to 10 Oe is applied along the hard axis. Under a stronger Hdc, the domain structure prominently changes, and the domain walls disappear when H dc exceeds ∼100 Oe. This confirms our previous finding that the initial permeability is ascribed only to magnetization rotation, with no contribution from domain wall motion
AB - Lorentz TEM observations of magnetic domain wall motion, as well as TEM observations of grain boundaries, were performed on spin-sprayed ferrite films #1 (Ni0.17Zn0.22Fe2.61O4) and #2 (Ni0.19Zn0.20Co0.03Fe2.58O 4), both 0.5 μm in thickness. They exhibit much higher natural resonance frequencies than the bulk ferrite and thus have been applied to gigahertz noise suppressors. Films #1 and #2 exhibit prominent and weak in-plane uniaxial magnetic anisotropy, respectively, which is induced along the liquid flow direction during spin-spraying. Both films have columnar crystallites with 100-200 nm widths aligned perpendicular to the film plane, and the boundaries of the crystallites have no pores or impurity phases. Therefore, the crystallites are magnetically exchange-coupled, which is responsible for the unusually high permeability and high natural resonance frequencies of the films. Under zero bias magnetic field, film #1 exhibits mosaic-shaped magnetic domains, whereas film #2 exhibits magnetic domains elongated along the easy magnetization axis, both several hundred nanometers in width. For both films the domain structure remains unchanged when an in-plane bias DC magnetic field, Hdc, of up to 10 Oe is applied along the hard axis. Under a stronger Hdc, the domain structure prominently changes, and the domain walls disappear when H dc exceeds ∼100 Oe. This confirms our previous finding that the initial permeability is ascribed only to magnetization rotation, with no contribution from domain wall motion
KW - Domain wall motion
KW - Electron microscopy
KW - Lorentz microscopy
KW - Magnetic domains
KW - Noise suppressors
KW - Spin-sprayed ferrite films
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U2 - 10.1002/tee.20187
DO - 10.1002/tee.20187
M3 - Article
AN - SCOPUS:34547176337
VL - 2
SP - 445
EP - 449
JO - IEEJ Transactions on Electrical and Electronic Engineering
JF - IEEJ Transactions on Electrical and Electronic Engineering
SN - 1931-4973
IS - 4
ER -