磁記錄材料ppt課件-資料下載頁(yè)
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【正文】 low anisotropy Large grains or high anisotropy Small bits requires small grains )(l o g~ 10 NS N R2 4 6 8 10 12 14020406080100120140CoCrPtHA MRPM RP erpen di cul ar M ed i a Ca nd i da t esCoPt3FePdCo/PdCo3PtCo/PtM nAlFe14Nd2BFePtCoPt HK (kOe)DP (nm)SmCo5 10 nm HAMA (Heat Assisted Magic Recording) Temperature Coercivity, Hc Hw limit RT Magic domains oriented in the direction of travel of the head. Longitudinal Recording Perpendicular Recording Soft underlayer ―mirrors‖ write head and makes it possible to write domains much closer together. Temperature Coercivity, Hc Hw limit RT J. P. Wang, Nat. Mater. 4, 191 (2022) New routine ——Tilted media New routine —— Bit Patterned Media Lithography vs. Self Organization Lithographically Defined ?Major obstacle is finding low cost means of making media Direct EBeam Write or DiBlock CoPolymer Idea: Use Pattern Assisted Assembly to establish circumferential tracks on discs FePt SelfOrganizing Media 6 nm FePt particles “9 Tb/in2“ ES, ECC and graded media Advantages of ECC media: ? Lower switching field : enhance Writability ? Dynamical tilting reversal : eliminates Noise ? Higher Ku hard layer: enhance Thermal stability Happl Hard layer (high Hk) provides the thermal stability Soft layer (low Hk) help switch the hard layer Interface sharp graded Domain wall nucleation, pression and depinning process at the hard/soft posite interface significantly reduces switching field. Domain wall High Hk Low Hk Hexc . Victora, IEEE Trans. Magn. 41, 537 (2022)。 D. Suess, Appl. Phys. Lett. 87, 012504 (2022)。 D. Suess, Appl. Phys. Lett. 89, 113105 (2022). 軟磁 /硬磁復(fù)合介質(zhì) 降低矯頑力，保持 /提高熱穩(wěn)定性， 解決了超高密度垂直磁記錄介質(zhì)的三難問(wèn) 題。 習(xí)題 ? 談?wù)剬?duì)磁記錄薄膜材料的認(rèn)識(shí)。 ? 提高硬盤盤片的記錄密度有哪些途徑？ ? 3. 為什么要用軟磁硬磁交換耦合薄膜？
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