Characterizing formation of interfacial domain wall and exchange coupling strength in laminated exchange coupled composites

Hou, Hao-Cheng; Kirby, Brian J.; Gao, Kai-Zhong; Lai, Chih‐Huang

doi:10.1063/1.4803038

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…The FORC distributions are thought to be highly sensitive to the interacting particles and have been widely used on nanocomposite magnets. [34][35][36][37] It was initially proposed as a method to identify the Preisach model parameters and was later extended as a model-independent technique to characterized the hysteresis in the magnetization reversals of the magnetic materials. [38,39] Subsequently, it has been proven to be a useful technique to model the behavior of hysteretic materials, including the determination of interactions in multiphase magnetic systems.…”

Section: Applied Field/koementioning

confidence: 99%

“…[31] The exchange-coupling between the hard-softmagnetic nanocomposite magnets based on the FORC method has been reported earlier. [34][35][36][37] When soft-and hard-magnetic layers are coupled with each other beyond a critical distance, the weak long-range dipolar interaction becomes dominant. According to the results of Cui et al [25] and Gabay et al, [47] the dipolar interaction may play an important role in combining the soft-and hard-magnetic phases.…”

Section: Applied Field/koementioning

confidence: 99%

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Anisotropic nanocomposite soft/hard multilayer magnets

Liu¹,

Zhang²

2017

Chinese Phys. B

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Experimental and theoretical researches on nanostructured exchange coupled magnets have been carried out since about 1988. Here, we review the structure and magnetic properties of the anisotropic nanocomposite soft/hard multilayer magnets including some new results and phenomena from an experimental point of view. According to the different component of the oriented hard phase in the nanocomposite soft/hard multilayer magnets, three types of magnets will be discussed: 1) anisotropic Nd 2 Fe 14 B based nanocomposite multilayer magnets, 2) anisotropic SmCo 5 based nanocomposite multilayer magnets, and 3) anisotropic rare-earth free based nanocomposite multilayer magnets. For each of them, the formation of the oriented hard phase, exchange coupling, coercivity mechanism, and magnetic properties of the corresponding anisotropic nanocomposite multilayer magnets are briefly reviewed, and then the prospect of realization of bulk magnets on new results of anisotropic nanocomposite multilayer magnets will be carried out.

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Section: Applied Field/koementioning

confidence: 99%

Section: Applied Field/koementioning

confidence: 99%

Anisotropic nanocomposite soft/hard multilayer magnets

Liu¹,

Zhang²

2017

Chinese Phys. B

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Magnetic interactions in anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer magnets

Dai

Liu

Zhao

et al. 2016

Journal of Applied Physics

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The magnetic properties and the possible interaction mechanisms of anisotropic soft- and hard-magnetic multilayers have been investigated by altering the thickness of different kinds of spacer layers. The metal Ta and the insulating oxides MgO, Cr2O3 have been chosen as spacer layers to investigate the characteristics of the interactions between soft- and hard-magnetic layers in the anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer system. The dipolar and exchange interaction between hard and soft phases are evaluated with the help of the first order reversal curve method. The onset of the nucleation field and the magnetization reversal by domain wall movement are also evident from the first-order-reversal-curve measurements. Reversible/irreversible distributions reveal the natures of the soft- and hard-magnetic components. Incoherent switching fields are observed and the calculations show the semiquantitative contributions of hard and soft components to the system. An antiferromagnetic spacer layer will weaken the interaction between ferromagnetic layers and the effective interaction length decreases. As a consequence, the dipolar magnetostatic interaction may play an important role in the long-range interaction in anisotropic multilayer magnets.

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Depth-Dependent Magnetization Profiles of Hybrid Exchange Springs

et al. 2014

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We report on the magnetization depth profile of a hybrid exchange spring system in which a Co/Pd multilayer with perpendicular anisotropy is coupled to a CoFeB thin film with in-plane anisotropy. The competition between these two orthogonal anisotropies promotes a strong depth dependence of the magnetization orientation. The angle of the magnetization vector is sensitive both to the strength of the individual anisotropies and to the local exchange constant, and is thus tunable by changing the thickness of the CoFeB layer and by substituting Ni for Pd in one layer of the Co/Pd stack. The resulting magnetic depth profiles are directly probed by element specific x-ray magnetic circular dichroism (XMCD) of the Co, Fe, and Ni layers located at different average depths. The experimental results are corroborated by micromagnetic simulations.PACS numbers: 75.30. Gw, 75.30.Et, 78.20.Ls, 75.70.Cn a Author to whom correspondence should be addressed. Electronic mail: anhntn@kth.se. 2The phenomenon of spin transfer torque (STT) [1][2][3], in which a spin-polarized current transfers angular momentum to a magnetic layer, has brought about novel applications such as spin torque oscillators (STOs) [4][5][6][7] and spin transfer torque magnetoresistive random access memory (STT-MRAM) [8][9][10]. While initially based on magnetic materials with in-plane (IP) magnetic anisotropy, the realization that such materials lead to unnecessarily high STT-MRAM switching currents, poor memory retention, poor scalability [11], and high-field operation of STOs [12], there is now a rapidly growing interest in fabricating STT devices based on perpendicular magnetic anisotropy (PMA) materials. Recent tailoring of PMA materials and their interfaces have demonstrated low switching currents, high switching speed, good thermal stability, future scalability [9,[13][14][15], and low-to zero-field operation of STOs [16][17][18][19][20].Building upon these successes, the natural extension of using PMA materials is to also investigate the potential of devices in which the magnetization is tilted with respect to the surface normal. Such materials allow for additional control of the magnetization dynamics in magnetic nanostructures [17,[21][22][23], and hint at yet improved STT-MRAM switching behavior and thermal stability [24][25][26][27][28][29]. For STOs, tilted materials offer a route to improve their microwave generation properties, both in terms of higher output power and low-to zero-field operation [17,[21][22][23]28,[30][31][32].Recently, tilted materials have also been shown to have potential for current-driven domain wall motion [33]. The influence of a tilted anisotropy is stronger than simply tilting the applied field [34] as a mere 5 degree misalignment between the free and the fixed layer in magnetic tunnel junctions (MTJs) can reduce the switching current by 36%, the switching time by 30%, and improve the switching current distribution [35].Materials with tilted anisotropies have been realized using collimated oblique sputtering [36], depos...

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Characterizing formation of interfacial domain wall and exchange coupling strength in laminated exchange coupled composites

Cited by 5 publications

References 23 publications

Anisotropic nanocomposite soft/hard multilayer magnets

Anisotropic nanocomposite soft/hard multilayer magnets

Magnetic interactions in anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer magnets

Depth-Dependent Magnetization Profiles of Hybrid Exchange Springs

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