Magnetization reversal of FePt based exchange coupled composite media

J. Wang; H. Sepehri-Amin; Y. K. Takahashi; S. Okamoto; S. Kasai; J. Y. Kim; T. Schrefl; K. Hono

doi:10.1016/j.actamat.2016.03.001

Magnetization reversal of FePt based exchange coupled composite media

J. Wang, H. Sepehri-Amin, Y. K. Takahashi, S. Okamoto, S. Kasai, J. Y. Kim, T. Schrefl, K. Hono

Research output: Contribution to journal › Article › peer-review

24 Citations (Scopus)

Abstract

Microstructure and magnetic properties of L1₀-ordered FePt-C nanogranular films capped with A1-disordered FePt layers with various thicknesses were investigated. After the growth of 9.5 nm thick L1₀-FePt-C granular layer on a MgO(001) single crystalline substrate at a substrate temperature of T_s = 600 °C, FePt capping layers with thicknesses, t_FePt, ranging from 2.7 to 8.6 nm were deposited at T_s = 400 °C. The coercivity of the L1₀-FePt-C/A1-FePt exchange coupled composite (ECC) media decreased from 4.9 to 1.4 T with increasing t_FePt. Evaluation of energy barrier, E_b, using the Sharrock equation indicated no degradation of thermal barrier in spite of the large reduction in the coercivity. The switching field distribution of the ECC media is significantly reduced from 23% for the single layer FePt-C granular film to 8% for the ECC media with t_FePt = 6.5 nm. Micromagnetic simulations showed the magnetization reversal of ECC media with t_FePt = 2 nm capping layer occurs by the coherent rotation while domain wall pinning becomes dominant for t_FePt ≥ 5 nm. The switching field distribution (SFD) of the ECC media is substantially decreased for t_FePt = 2 nm. Low coercivity with high E_b and improved SFD observed from the ECC media makes them promising as high areal density recording media for both perpendicular magnetic recording (PMR) and heat assisted magnetic recording (HAMR).

Original language	English
Pages (from-to)	47-55
Number of pages	9
Journal	Acta Materialia
Volume	111
DOIs	https://doi.org/10.1016/j.actamat.2016.03.001
Publication status	Published - 2016 Jun 1

Keywords

Energy barrier
Exchange coupled composite media
FePt
Magnetic recording media
Micromagnetic simulation
Switching field distribution

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10.1016/j.actamat.2016.03.001

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@article{e20753386706467d8ee3c08ebeca4c48,

title = "Magnetization reversal of FePt based exchange coupled composite media",

abstract = "Microstructure and magnetic properties of L10-ordered FePt-C nanogranular films capped with A1-disordered FePt layers with various thicknesses were investigated. After the growth of 9.5 nm thick L10-FePt-C granular layer on a MgO(001) single crystalline substrate at a substrate temperature of Ts = 600 °C, FePt capping layers with thicknesses, tFePt, ranging from 2.7 to 8.6 nm were deposited at Ts = 400 °C. The coercivity of the L10-FePt-C/A1-FePt exchange coupled composite (ECC) media decreased from 4.9 to 1.4 T with increasing tFePt. Evaluation of energy barrier, Eb, using the Sharrock equation indicated no degradation of thermal barrier in spite of the large reduction in the coercivity. The switching field distribution of the ECC media is significantly reduced from 23% for the single layer FePt-C granular film to 8% for the ECC media with tFePt = 6.5 nm. Micromagnetic simulations showed the magnetization reversal of ECC media with tFePt = 2 nm capping layer occurs by the coherent rotation while domain wall pinning becomes dominant for tFePt ≥ 5 nm. The switching field distribution (SFD) of the ECC media is substantially decreased for tFePt = 2 nm. Low coercivity with high Eb and improved SFD observed from the ECC media makes them promising as high areal density recording media for both perpendicular magnetic recording (PMR) and heat assisted magnetic recording (HAMR).",

keywords = "Energy barrier, Exchange coupled composite media, FePt, Magnetic recording media, Micromagnetic simulation, Switching field distribution",

author = "J. Wang and H. Sepehri-Amin and Takahashi, {Y. K.} and S. Okamoto and S. Kasai and Kim, {J. Y.} and T. Schrefl and K. Hono",

note = "Funding Information: This work was supported in part by IDEMA-ASTC (Grant No: 2011-051 ), Seagate UPAC and the Grant-in-Aid (B) (Grant No. 26289232 ). Publisher Copyright: {\textcopyright} 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.",

year = "2016",

month = jun,

day = "1",

doi = "10.1016/j.actamat.2016.03.001",

language = "English",

volume = "111",

pages = "47--55",

journal = "Acta Materialia",

issn = "1359-6454",

publisher = "Elsevier Ltd.",

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TY - JOUR

T1 - Magnetization reversal of FePt based exchange coupled composite media

AU - Wang, J.

AU - Sepehri-Amin, H.

AU - Takahashi, Y. K.

AU - Okamoto, S.

AU - Kasai, S.

AU - Kim, J. Y.

AU - Schrefl, T.

AU - Hono, K.

N1 - Funding Information: This work was supported in part by IDEMA-ASTC (Grant No: 2011-051 ), Seagate UPAC and the Grant-in-Aid (B) (Grant No. 26289232 ). Publisher Copyright: © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

PY - 2016/6/1

Y1 - 2016/6/1

N2 - Microstructure and magnetic properties of L10-ordered FePt-C nanogranular films capped with A1-disordered FePt layers with various thicknesses were investigated. After the growth of 9.5 nm thick L10-FePt-C granular layer on a MgO(001) single crystalline substrate at a substrate temperature of Ts = 600 °C, FePt capping layers with thicknesses, tFePt, ranging from 2.7 to 8.6 nm were deposited at Ts = 400 °C. The coercivity of the L10-FePt-C/A1-FePt exchange coupled composite (ECC) media decreased from 4.9 to 1.4 T with increasing tFePt. Evaluation of energy barrier, Eb, using the Sharrock equation indicated no degradation of thermal barrier in spite of the large reduction in the coercivity. The switching field distribution of the ECC media is significantly reduced from 23% for the single layer FePt-C granular film to 8% for the ECC media with tFePt = 6.5 nm. Micromagnetic simulations showed the magnetization reversal of ECC media with tFePt = 2 nm capping layer occurs by the coherent rotation while domain wall pinning becomes dominant for tFePt ≥ 5 nm. The switching field distribution (SFD) of the ECC media is substantially decreased for tFePt = 2 nm. Low coercivity with high Eb and improved SFD observed from the ECC media makes them promising as high areal density recording media for both perpendicular magnetic recording (PMR) and heat assisted magnetic recording (HAMR).

AB - Microstructure and magnetic properties of L10-ordered FePt-C nanogranular films capped with A1-disordered FePt layers with various thicknesses were investigated. After the growth of 9.5 nm thick L10-FePt-C granular layer on a MgO(001) single crystalline substrate at a substrate temperature of Ts = 600 °C, FePt capping layers with thicknesses, tFePt, ranging from 2.7 to 8.6 nm were deposited at Ts = 400 °C. The coercivity of the L10-FePt-C/A1-FePt exchange coupled composite (ECC) media decreased from 4.9 to 1.4 T with increasing tFePt. Evaluation of energy barrier, Eb, using the Sharrock equation indicated no degradation of thermal barrier in spite of the large reduction in the coercivity. The switching field distribution of the ECC media is significantly reduced from 23% for the single layer FePt-C granular film to 8% for the ECC media with tFePt = 6.5 nm. Micromagnetic simulations showed the magnetization reversal of ECC media with tFePt = 2 nm capping layer occurs by the coherent rotation while domain wall pinning becomes dominant for tFePt ≥ 5 nm. The switching field distribution (SFD) of the ECC media is substantially decreased for tFePt = 2 nm. Low coercivity with high Eb and improved SFD observed from the ECC media makes them promising as high areal density recording media for both perpendicular magnetic recording (PMR) and heat assisted magnetic recording (HAMR).

KW - Energy barrier

KW - Exchange coupled composite media

KW - FePt

KW - Magnetic recording media

KW - Micromagnetic simulation

KW - Switching field distribution

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U2 - 10.1016/j.actamat.2016.03.001

DO - 10.1016/j.actamat.2016.03.001

M3 - Article

AN - SCOPUS:84961616811

SN - 1359-6454

VL - 111

SP - 47

EP - 55

JO - Acta Materialia

JF - Acta Materialia

ER -

Magnetization reversal of FePt based exchange coupled composite media

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Keywords

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