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Microstructure Engineering and Therm...

Xu, Chengchao,

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Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology // Chengchao Xu.
Author:	Xu, Chengchao,
Description:	1 electronic resource (167 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
Contained By:	Dissertations Abstracts International85-12B.
Subject:	Electrical engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31300241
ISBN:	9798382838427

Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology /
Xu, Chengchao,

Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology /Chengchao Xu. - 1 electronic resource (167 pages)

Source: Dissertations Abstracts International, Volume: 85-12, Section: B.

Heat-assisted magnetic recording (HAMR) is a next-generation technology enabling further increases in areal densities of hard disk drives beyond 1 Tb/in2 . HAMR relies on a novel recording medium composed of chemically ordered L10-FePt magnetic grains separated by insulating, thermally resistive grain boundary materials (GBMs). Achieving areal densities up to 4 Tb/in2 requires optimal media design with FePt grains of 6-8 nm diameter and high aspect ratios (>2.0) fully encircled by GBMs. This research aims to develop L10-FePt based HAMR media exhibiting the desired granular microstructure using innovative GBM materials and optimized deposition processes. Initially, a bilayer media design of FePt-BN/FePt-SiOx was systematically studied by varying SiOx compositions and deposition temperatures. An optimized graded deposition enabled growth of 11.5 nm tall columnar FePt grains (7 nm diameter) encircled by SiOx GBMs. Crystalline hexagonal boron nitride (h-BN) was then explored as a high thermal stability GBM, forming a unique FePt-(h-BN) core-shell nanostructure at temperatures >600℃. The substrate bias facilitates the formation of h-BN nanosheets in grain boundary regions, which promote columnar and coherent FePt grain growth up to 16 nm thickness with a record-high grain aspect ratio of 2.5. Varying h-BN content allowed tuning FePt grain sizes from 4-7 nm with high areal densities up to 2.96 x 104µm-2 . To investigate thermal transport in this FePt-(h-BN) material system, a model structure of [h-BN/FePt] multilayer thin films were fabricated and characterized. Thermal measurements using the three-omega method revealed an ultralow cross-plane thermal conductivity of 0.6 W/(m ∙ K) , dominated by the low thermal boundary conductance across van der Waals interfaces between h-BN basal planes and ordered FePt. The thermal boundary conductance for [FePt/h-BN/FePt] contact was estimated as 67.9 MW/(m2 ∙ K). Other 2D materials like graphene, WS2, and MoS2 were also explored as potential GBMs, exhibiting distinct growth behaviors when incorporated into the FePt films. This research provides comprehensive insights into microstructure engineering and thermal properties of FePt-based HAMR media using novel GBM materials and deposition processes. The findings establish guidelines for further optimization towards ultrahigh-density magnetic recording up to 4 Tb/in2 areal densities by elucidating microstructure-property relationships and growth mechanisms.

English

ISBN: 9798382838427Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Magnetic recording

Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology /
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245 1 0 $a Microstructure Engineering and Thermal Properties of FePt-Based Media for Heat-Assisted Magnetic Recording (HAMR) Technology / $c Chengchao Xu.
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300 $a 1 electronic resource (167 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 85-12, Section: B.
500 $a Advisors: Zhu, Jian-Gang; Laughlin, David E. Committee members: Bain, James A.; Bertero, Gerardo G.
502 $b Ph.D. $c Carnegie Mellon University $d 2024.
520 $a Heat-assisted magnetic recording (HAMR) is a next-generation technology enabling further increases in areal densities of hard disk drives beyond 1 Tb/in2 . HAMR relies on a novel recording medium composed of chemically ordered L10-FePt magnetic grains separated by insulating, thermally resistive grain boundary materials (GBMs). Achieving areal densities up to 4 Tb/in2 requires optimal media design with FePt grains of 6-8 nm diameter and high aspect ratios (>2.0) fully encircled by GBMs. This research aims to develop L10-FePt based HAMR media exhibiting the desired granular microstructure using innovative GBM materials and optimized deposition processes. Initially, a bilayer media design of FePt-BN/FePt-SiOx was systematically studied by varying SiOx compositions and deposition temperatures. An optimized graded deposition enabled growth of 11.5 nm tall columnar FePt grains (7 nm diameter) encircled by SiOx GBMs. Crystalline hexagonal boron nitride (h-BN) was then explored as a high thermal stability GBM, forming a unique FePt-(h-BN) core-shell nanostructure at temperatures >600℃. The substrate bias facilitates the formation of h-BN nanosheets in grain boundary regions, which promote columnar and coherent FePt grain growth up to 16 nm thickness with a record-high grain aspect ratio of 2.5. Varying h-BN content allowed tuning FePt grain sizes from 4-7 nm with high areal densities up to 2.96 x 104µm-2 . To investigate thermal transport in this FePt-(h-BN) material system, a model structure of [h-BN/FePt] multilayer thin films were fabricated and characterized. Thermal measurements using the three-omega method revealed an ultralow cross-plane thermal conductivity of 0.6 W/(m ∙ K) , dominated by the low thermal boundary conductance across van der Waals interfaces between h-BN basal planes and ordered FePt. The thermal boundary conductance for [FePt/h-BN/FePt] contact was estimated as 67.9 MW/(m2 ∙ K). Other 2D materials like graphene, WS2, and MoS2 were also explored as potential GBMs, exhibiting distinct growth behaviors when incorporated into the FePt films. This research provides comprehensive insights into microstructure engineering and thermal properties of FePt-based HAMR media using novel GBM materials and deposition processes. The findings establish guidelines for further optimization towards ultrahigh-density magnetic recording up to 4 Tb/in2 areal densities by elucidating microstructure-property relationships and growth mechanisms.
546 $a English
590 $a School code: 0041
650 4 $a Electrical engineering. $3 649834
650 4 $a Applied physics. $3 3343996
650 4 $a Materials science. $3 543314
650 4 $a Condensed matter physics. $3 3173567
653 $a Magnetic recording
653 $a Nanocomposite materials
653 $a Sputtering
653 $a Thin film deposition
653 $a Grain boundary materials
690 $a 0794
690 $a 0544
690 $a 0215
690 $a 0611
710 2 $a Carnegie Mellon University. $b Electrical and Computer Engineering. $e degree granting institution. $3 3820472
720 1 $a Zhu, Jian-Gang $e degree supervisor.
720 1 $a Laughlin, David E. $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-12B.
790 $a 0041
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31300241