Thermally assisted magnetic recording on flux-detectable RE-TM media

Abstract

We studied a thermally assisted magnetic recording on flux-detectable RE-TM media. This recording scheme has a close affinity with near-field optics such as solid immersion lens (SIL) optics and scanning near-field optical microscope (SNOM)-type optics. The requirements for high-density thermo-magnetic recording and a novel near-field optical head were discussed.Index Terms-Magneto-optical disk, near field, RE-TM, thermo-magnetic recording.

Advanced hybrid recording media

“…In the thermo-magnetic writing process, magnetic domains are formed on the recording layer first and copied to the readout layer after the film temperature falls. Write-read experiments on this exchange-coupled double-layer MO media confirmed it is suitable for hybrid recording with an areal density of 60 Gbit/in 2 [24] .…”

“…This kind of thermal design has been applied experimentally to the single-layer and exchange-coupled double layer amorphous MO media for hybrid recording and the heat-sinking layers are AlN and Al layer, respectively, although more intensive experimental investigation is needed on the effect of heat-sinking layer on the thermal response speed of hybrid recording media [21,24] . [14] >8 447…”

“…≈ 400 ----10-100 FePt [13] 41 1125 ----770 ----Fe 25 Ni 30 Pt 45 [13] 16 795 ----490 90 FePt/FeRh [15,16] 8 100 ----450 500 CoTbAg [22] 3.1 310 255 473 ----C/TbFeCo/AlN [21] ＞ 20 70 ----523 ----SmTbCo/Cr [27] 4.7 385 ----483 ----TM rich 0.95 ----113 473 ----SiN/TM-rich-TbFeCo/RE -rich-TbFeCo/SiN [25] RE rich 4.6 447 ≈ 400 543 ----TbDyFeCo ＜ 2 260 ----513 ----SiN/Al/SiN/TbDyFeCo/ TbFeCo/SiN [24] TbFeCo ＞ 10 ＜ 100 ----573 ----(Note: H c is the coercivity at room temperature; M s saturation magnetization; M r remenant magnetization; T c Curie temperature; dH k /dT temperature coefficient of the switching field at writing field. )…”

“…With increasing Sm composition, it was found the M s increases without compromising a lot in H c , and M s as high as 385emu/cm 3 31 Co 69 (120nm)/Cr(180nm) films [27] . Besides the single layer MO media, exchange-coupled double layer amorphous MO media has attracted much attention [23][24][25] . The typical film structure is shown in Fig.6 been obtained in such kind of media [25] .…”

Integrated near-field optical head for hybrid recording

“…However, this approach will ultimately cause the media to be unrecordable with conventional inductive write heads because the required write field is too high. To overcome this problem, hybrid recording, which combines thermal magnetic recording and magneto-resistive reading, was proposed and has since attracted a lot of interest as the next generation recording technology [2]. In this hybrid recording system, the writing process is similar to the conventional magneto-optical recording, where a focused laser spot is used to heat the recording media to lower its coercivity during writing.…”