Exchange spring media for perpendicular recording

Suess, Dieter; Schrefl, T.; Fähler, S.; Kirschner, M.; Hrkac, G.; Dorfbauer, F.; Fidler, J.

doi:10.1063/1.1951053

Cited by 333 publications

(192 citation statements)

References 15 publications

(11 reference statements)

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“…One such active field of research is the exchange spring magnet [3][4][5][6][7] , where high saturation magnetization of the soft and the high magnetic anisotropy of the hard magnetic phases are exchange coupled in the nanometric scale. Both the experimental studies and the Micromagnetic calculations [8][9][10][11] reveal that significant improvements in terms of magnetic energy product (BH) max can be achieved using the exchange spring magnet.…”

Section: Introductionmentioning

confidence: 99%

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Roy¹,

Sreenivasulu²,

Kumar³

2013

Applied Physics Letters

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The magnetization behaviour of the soft Cobalt Ferrite-hard Strontium Ferrite nanocomposite is tuned from the non exchange spring nature to the exchange spring nature, by controlling the particle size of the soft Cobalt Ferrite in the Cobalt Ferrite: Strontium Ferrite (1:8) nanocomposite. The relative strength of the interaction governing the magnetization process in the nanocomposites is investigated using Henkel plot and First Order Reversal Curve (FORC) method. The FORC method has been utilized to understand the magnetization reversal behaviour as well as the extent of the irreversible magnetization present in both the nanocomposites having smaller and larger particle size of the Cobalt Ferrite. The magnetization process is primarily controlled by the domain wall movement in the nanocomposites. Using the FORC distribution in the (H a , H b ) co-ordinate, the onset of the nucleation field, invasion of the domain wall from the soft to the hard phase, domain wall annihilation and the presence of the reversible magnetization with the applied reversal field for both the nanocomposites has been investigated. It has been found that for the composite having lower particle size of the soft phase shows a single switching behaviour corresponding to the coherent reversal of the both soft and hard phases. However, the composite having higher Cobalt Ferrite particle size shows two peak behaviour in the FORC distribution resembling individual switching of the soft and hard phases. The FORC distribution in (H u , H c ) co-ordinate and the Henkel measurement confirms the dominant exchange interaction in the nanocomposites exhibiting exchange spring behaviour where as the occurrence of both the dipolar and exchange interaction is substantiated for the non exchange coupled nanocomposite. The asymmetric nature of the FORC distribution at H c = 0 Oe for both the nanocomposites validates the intercoupled nature of the reversible and irreversible magnetizations in both the nanocomposites. It is also concluded that the contribution of the reversible magnetization is more in the nanocomposite having lower particle size of the Cobalt Ferrite compared to the nanocomposite having higher particle size of the Cobalt Ferrite.

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Section: Introductionmentioning

confidence: 99%

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Roy¹,

Sreenivasulu²,

Kumar³

2013

Applied Physics Letters

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“…In the last decade, various methods have been proposed to solve this problem, e.g., heat-assisted recording 8 or the application of anisotropy-graded 9 and exchange-coupled media. 10 In this study, we explore an alternative way to tailor the anisotropy of such materials. Our strategy is based on the application of the magnetoelectric effect [11][12][13] between adjacent ferromagnetic and ferroelectric films.…”

mentioning

confidence: 99%

Tailoring magnetic anisotropy at the ferromagnetic/ferroelectric interface

Duan¹,

Velev²,

Sabirianov³

et al. 2008

Applied Physics Letters

145

122

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It is predicted that magnetic anisotropy of a thin magnetic film may be affected by the polarization of a ferroelectric material. Using a Fe∕BaTiO3 bilayer as a representative model and performing first-principles calculations, we demonstrate that a reversal of the electric polarization of BaTiO3 produces a sizable change in magnetic anisotropy energy of Fe films. Tailoring the magnetic anisotropy of a nanomagnet by an adjacent ferroelectric material may yield entirely new device concepts, such as electric-field controlled magnetic data storage.

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“…Recently, the formation of exchange coupled composites of soft and hard phases was proposed to reduce switching field. 3,4 The switching field could be further reduced in a graded anisotropy medium where anisotropy constant varies smoothly across the bit. 5 FePt is well known hard magnetic material with tetragonal ground state L1 0 structure and it preserves its bulk magnetic properties at nanoscale.…”

mentioning

confidence: 99%

Tailoring magnetocrystalline anisotropy of FePt by external strain

Lukashev¹,

Horrell²,

Sabirianov³

2012

Journal of Applied Physics

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We propose using strain assisted reduction in anisotropy of FePt to control magnetization reversal in the writing on the magnetic storage devices. Our first-principles calculations show 21% decrease of the magnetocrystalline anisotropy energy (MAE) with application of 1.5% tensile biaxial strain. The reduction of MAE is primarily due to the change of the c/a ratio and to some extent due to the increase in volume. We propose building bilayer (or heterostructure) of FePt and piezoelectric film. This system is expected to allow the control of anisotropy constant by applying electric field to the system. Finally, we discuss the possibility of forming medium using bi-layer of FePt and soft magnetic material with the gradient of anisotropy constant.

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Exchange spring media for perpendicular recording

Cited by 333 publications

References 15 publications

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Tailoring magnetic anisotropy at the ferromagnetic/ferroelectric interface

Tailoring magnetocrystalline anisotropy of FePt by external strain

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