Control of Magnetic Anisotropy by Lattice Distortion in Cobalt Ferrite Thin Film

Onoda, Hiroshige; Sukegawa, Hiroaki; Kita, Eiji; Yanagihara, Hideto

doi:10.1109/tmag.2018.2833880

Cited by 15 publications

(9 citation statements)

References 22 publications

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“…Moreover, the extremely small local deformation of the lattice structure around the TM ions produces a substantial change in the MA. The calculated results agree well with the experimental values [24][25][26][27][28][29][30]. In the present study, we apply this method to calculate the local MA produced by M 2 + in M 2 Y ferrites and compare the total resulting MA with the observed data by identifying possible occupation sites of M 2 + .…”

Section: Introductionsupporting

confidence: 82%

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Inoue¹,

Koizumi²,

Nakamura³

et al. 2020

J. Phys. D: Appl. Phys.

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We study magnetic anisotropy (MA) of the Y-type ferrites using an electron theory at 0 K that was previously applied to M-type and spinel ferrites. In our calculation, we consider the local lattice structure around M2 + ions in the ferrites (M2Y ferrites), where M represents Fe, Co, Ni and Cu. The calculated MA energy, difference between magnetic energies of states with magnetisation Ms parallel and perpendicular to c-axis of the hexagonal lattice, is compared with the experimental values by identifying possible occupation sites of M2 +. The calculated MA energies of Co2Y and Ni2Y are − 0.33 and − 0.39 MJ m−3, respectively. The negative sign indicates that Ms is within the c-plane of the lattice. We have analyzed in detail how the local lattice structure around M2 + affects the MA of the M2Y ferrites. The c-plane MA constant K3 of Co2Y is also calculated and compared with the experimental value. In addition, the MAs of Mg2Y and Zn2Y are examined. The findings of this study may contribute to design Y-type ferrites which are applicable to hyper-frequency regime.

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Section: Introductionsupporting

confidence: 82%

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Inoue¹,

Koizumi²,

Nakamura³

et al. 2020

J. Phys. D: Appl. Phys.

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“…[14] Extensive magneto-elastic effects have been reported, along with the existence of a large orbital moment in Co 2+ . [15][16][17][18][19][20][21][22][23][24][25][26] The large cubic MA of bulk CFO has been elucidated theoretically using a single-ion model; the cubic and local trigonal lattice symmetries split the down-spin t 2g state into a singly occupied and doubly degenerate state with a magnetic quantum number ∼ ±1; moreover, the degeneracy is lifted by SOI. [27,28] Once uniaxial lattice distortion is introduced as shown in Figure 1(b), a large PMA should arise because of the magneto-elastic effects.…”

Section: Introductionmentioning

confidence: 99%

“…We have recently found that Mg 2 SnO 4 (001) (MSO), an oxide with a spinel structure, is suitable for the application of large tensile stresses in CFO thin films. [25,26] In this study, we attempted to quantitatively control the lattice distortion of CFO thin films to induce large positive K u values in the absence of platinum group or rare-earth elements. Two methods were adopted to introduce the distortion into CFO thin films on MSO buffer layers: control of the CFO thickness and control of the MSO lattice constants.…”

Section: Introductionmentioning

confidence: 99%

“…[14] Extensive magneto-elastic effects have been reported, along with the existence of a large orbital moment in Co 2+ . [15][16][17][18][19][20][21][22][23][24][25][26] The large cubic MA of bulk CFO has been elucidated theoretically using a single-ion model; the cubic and local trigonal lattice symmetries split the down-spin t 2g state into a singly Perpendicular magnetic anisotropy (PMA) energy up to K u = 6.1 ± 0.8 MJm −3 is demonstrated in this study by inducing large lattice distortion exceeding 3% at room temperature in epitaxially distorted cobalt ferrite Co 0.73 Fe 2.18 O 4 (001) thin films. Although the thin film materials include no rare-earth elements or noble metals, the observed K u is larger than that of the neodymium-iron-boron compounds for high-performance permanent magnets.…”

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confidence: 99%

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Strain Engineering of Magnetic Anisotropy in Epitaxial Films of Cobalt Ferrite

Onoda

Sukegawa

Inoue

et al. 2021

Adv Materials Inter

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crucial for application in functional spintronic devices and high-density magnetic recording technology. [3][4][5][6][7] To explore or synthesize magnetic materials with high coercivity, materials with large MAs are required for obtaining high-performance permanent magnets. Because MA is indirectly proportional to the symmetry of the crystal, materials with lower crystal symmetry are promising for application as high-MA compounds. Generally, the physical origin of large MAs is spin-orbit interaction (SOI), calculated as the inner product of orbital (L ) and spin angular momenta (S) with an interaction constant λ. For a given spin moment, the magnitude of SOI is determined by λ and the expected value of the orbital angular momentum. Magnetic materials composed of noble metals often exhibit large MAs, attributed to the large λ values of noble metals. In contrast, the large MAs of permanent magnets composed of rare-earth elements are attributed to their large values of λ and orbital angular momenta. [3,[8][9][10][11][12][13] In transition metal alloys or compounds that do not contain heavy or rare-earth elements, L is often quenched in a crystal field. Consequently, magnetic materials with large MAs are rare. In contrast, a certain amount of orbital angular momentum is sometimes retained in oxides, owing to the localized character of the wave functions of transition metal ions in the crystal field. The magnitude of the orbital angular momentum is influenced by the electronic configurations of the magnetic ions; therefore, the MAs of magnetic oxides can be induced/enhanced by introducing asymmetry, such as lattice deformations. This phenomenon can be considered to be magneto-elastic in nature because the change in magnetic state is induced by lattice deformation. Furthermore, a large uniaxial MA can be realized by uniaxial lattice deformation. The epitaxial distortion arising from the lattice mismatch between oxide thin films and their substrates can be employed to effectively induce lattice distortion.Co x Fe 3−x O 4 (CFO) has a cubic lattice, as shown in Figure 1a, and exhibits a large cubic MA with a Néel temperature of 769 K for x = 1.0 and has been reportedly used as permanent magnets. [14] Extensive magneto-elastic effects have been reported, along with the existence of a large orbital moment in Co 2+ . [15][16][17][18][19][20][21][22][23][24][25][26] The large cubic MA of bulk CFO has been elucidated theoretically using a single-ion model; the cubic and local trigonal lattice symmetries split the down-spin t 2g state into a singly Perpendicular magnetic anisotropy (PMA) energy up to K u = 6.1 ± 0.8 MJm −3 is demonstrated in this study by inducing large lattice distortion exceeding 3% at room temperature in epitaxially distorted cobalt ferrite Co 0.73 Fe 2.18 O 4 (001) thin films. Although the thin film materials include no rare-earth elements or noble metals, the observed K u is larger than that of the neodymium-iron-boron compounds for high-performance permanent magnets. The large PMA is attributed to the sig...

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“…[4][5][6][7][8][9][10][11] Investigation of magnetic anisotropy by the magnetoelastic effect has been conducted by preparing CFO thin films on various substrates to apply tetragonal strain. [7][8][9][10][11][12][13][14][15][16][17] Since the lattice constant of CFO is slightly smaller than twice the lattice constant of MgO, and a lattice mismatch occurs when epitaxially grown. Consequently, a CFO thin film prepared on a MgO single crystal substrate exhibited a large perpendicular magnetic anisotropy.…”

Section: Introductionmentioning

confidence: 99%

(001) preferred oriented CoFe₂O₄thin films on glass and Si substrates prepared by the metal-organic decomposition method

Yasuda

Nishikawa

Ishibashi

2019

Jpn. J. Appl. Phys.

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It has been reported that cobalt ferrite (CoFe2O4: CFO) thin films prepared on MgO single crystal substrates exhibited high perpendicular magnetic anisotropy. In this paper, we report on (001) preferred oriented CFO thin films prepared on glass and Si substrates using the metal-organic decomposition (MOD) method. It was found that (001) preferred oriented CFO thin films were obtained using pre-annealing temperatures of 310 °C–330 °C for 30 min, followed by annealing for crystallization at 700 °C for 10 h. CFO thin films prepared with various pre-annealing temperatures were evaluated using a magneto-optical spectrometer, X-ray diffraction and electron backscattered diffraction combined with field emission scanning electron microscopy.

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Control of Magnetic Anisotropy by Lattice Distortion in Cobalt Ferrite Thin Film

Cited by 15 publications

References 22 publications

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Strain Engineering of Magnetic Anisotropy in Epitaxial Films of Cobalt Ferrite

(001) preferred oriented CoFe₂O₄thin films on glass and Si substrates prepared by the metal-organic decomposition method

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Control of Magnetic Anisotropy by Lattice Distortion in Cobalt Ferrite Thin Film

Cited by 15 publications

References 22 publications

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

Strain Engineering of Magnetic Anisotropy in Epitaxial Films of Cobalt Ferrite

(001) preferred oriented CoFe2O4thin films on glass and Si substrates prepared by the metal-organic decomposition method

Contact Info

Product

Resources

About

(001) preferred oriented CoFe₂O₄thin films on glass and Si substrates prepared by the metal-organic decomposition method