Magnetization curling in a finite cylinder

Ishii, Y.; Satô, Masayoshi

doi:10.1063/1.342712

Cited by 18 publications

(10 citation statements)

References 11 publications

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“…[44] While the 15 and 20 nm Co NW samples contain NWs with diameters larger than the coherent limit (≈14.6 nm), a curling reversal mode can be expected. [43,45] In congruence with the theory, the magnetization reversal mechanisms examined as a function of the diameter display a critical wire diameter (d c ≈ 15 nm), below which the magnetization reversal occurred via a coherent rotation-type and above which the magnetization reversal occurred via a curling reversal-type mode. Thus, the decrease in wire diameter from 20 to 8 nm of single-domain nanowires leads to a gradual increase of coercivity to the high value of 12.6 kOe.…”

Section: (4 Of 10)supporting

confidence: 57%

Extraordinary Magnetic Hardening in Nanowire Assemblies: the Geometry and Proximity Effects

Mohapatra

Xing

Elkins

et al. 2021

Adv Funct Materials

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Brown's theorem on coercivity of ferromagnetic materials has predicted that the coercivity level is substantially higher than in practice for all the materials studied in experiments in the past seven decades, which is known as the Brown's paradox. In this paper, a system with a coercivity close to the one predicted by Brown's theorem is investigated. Cobalt nanowires are obtained by chemical synthesis that give rise to coercive forces significantly higher than the magnetocrystalline anisotropy field, verifying the Brown's theorem. It is found that the coercivity is strongly dependent on the nanowire diameter, the alignment of the wires in an assembly, and the packing density of the assembly. An analysis based on the current experimental results and related literature reveals a coercivity ceiling in consideration of geometrical dimensions and the effective magnetic anisotropy. Quantitative information is obtained about the proximity effect on the coercivity and the magnetization which shows the correlation between the energy product and the packing density. Furthermore, it is found that by coating the nanowires with Fe, the energy density can be enhanced. These findings provide a guideline for materials design of future high‐performance permanent magnets that take advantage of shape anisotropy at the nanoscale.

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Section: (4 Of 10)supporting

confidence: 57%

Extraordinary Magnetic Hardening in Nanowire Assemblies: the Geometry and Proximity Effects

Mohapatra

Xing

Elkins

et al. 2021

Adv Funct Materials

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“…The magnetization-curling model, first proposed by Frei et al, 1 has been used to interpret the magnetization mechanism of particles [2][3][4][5][6] and of films with perpendicular magnetization. [7][8][9][10][11][12] In these works, however, no magnetocrystalline anisotropy is taken into account in the case of an inclined applied field.…”

Section: Introductionmentioning

confidence: 99%

Magnetization curling in films used for perpendicular magnetic recording

Ishii

Hasegawa

Saito

et al. 1997

Journal of Applied Physics

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Articles you may be interested inReduction of grain size and intergrain interaction in Fe Pt ∕ Pt ∕ Cr trilayer thin films for perpendicular magnetic recording J. Appl. Phys. 99, 08E709 (2006); 10.1063/1.2171941BaM/Pt multilayered films with fine grains and large perpendicular magnetic anisotropy for high density recording media Co ferrite films with excellent perpendicular magnetic anisotropy and high coercivity deposited at low temperatureThe magnetization-curling mode in a columnar-structure film with perpendicular magnetization is studied on the assumption that the film is a two-dimensional array of cylinders. The angular dependence of the nucleation field H N is calculated by the Ritz method and compared with that for the coherent-rotation mode. It is found that the magnetization rotates in the curling mode for a large reduced radius S and in the coherent-rotation mode for a small S. The angular dependence of H N is different from that in an infinite cylinder. If S is large, the magnetization rotates in the curling mode for any value of 0 , where 0 is the angle between the applied field and the cylinder axis. When S is medium, the magnetization rotates in the coherent-rotation mode for a small 0 and in the curling mode for a large 0 .

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“…Such hysteresis loops are also obtained for the curling mode in a finite cylinder. 4 It is also found from Fig. 2͑a͒ that the spins are aligned when H is applied along the z axis and increases with an increase in H along the negative z axis.…”

Section: Numerical Results and Discussionmentioning

confidence: 73%

“…The magnetization curling mode was first proposed by Frei et al 1 Based on this mode, the magnetization processes of particles [2][3][4] and perpendicular magnetic films [5][6][7][8] have been reported. Work on the magnetization curling was reviewed by Aharoni.…”

Section: Introductionmentioning

confidence: 99%

Magnetization curling in a disk with a uniaxial anisotropy

Ishii

Nakazawa

1997

Journal of Applied Physics

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The role of rotatable anisotropy in the asymmetric magnetization reversal of exchange biased NiO/Ni bilayers To investigate the behavior of the magnetization in a single-domain disk with a uniaxial magnetocrystalline anisotropy, the assumption is made that the magnetization changes its direction by the magnetization curling mode. In this mode, the deviation of the spin from the z axis at (r,,z) in the cylindrical coordinate is given by ϭa 0 ϩa 1 (r/R)ϩa 2 (r/R) 2 ϩa 3 (r/R) 3 , where R is the radius of the disk and a 0 -a 3 are coefficients. An equilibrium spin configuration is obtained for a given applied field H by finding a set of values of a 0 -a 3 that minimize the magnetic energy of the disk. Carrying out this procedure for various H, a hysteresis loop and the coercive force are obtained. It is found that the configuration in which the spins deviate from the z axis can be stable and, therefore, the hysteresis loop is not rectangular, even though an applied field is along the z axis. The deviation is larger for the spins near the lateral surface of the disk, and the spins near the center do not incline easily. Moreover, for a large magnetocrystalline anisotropy and a large diameter, the magnetization changes its direction upward and downward alternately with r. The nucleation field calculated with the present model agrees well with that of the curling mode in an oblate spheroid.

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Magnetization curling in a finite cylinder

Cited by 18 publications

References 11 publications

Extraordinary Magnetic Hardening in Nanowire Assemblies: the Geometry and Proximity Effects

Extraordinary Magnetic Hardening in Nanowire Assemblies: the Geometry and Proximity Effects

Magnetization curling in films used for perpendicular magnetic recording

Magnetization curling in a disk with a uniaxial anisotropy

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