Magnetic properties and recording characteristics of high magnetization exchange-coupled double-layer TbFeCo for magnetic flux reading optical recording

The magnetic properties and recording characteristics of exchange-coupled d ouble-layer (ECDL) disks consisting of a transition metal-rich TbFeCo reado ut layer with high magnetization and a recording layer were studied for mag netic flux reading optical recording. The effective coercivity of ECDL with rare-earth (recording)/transition metal-rich (readout) films could be grea tly enhanced from 1.7 to 7.6kOe through exchange coupling between two activ e layers. Moreover, ECDL disks possess a lower recording bias field (100 Oe ) and a lower onset field (- 150 Oe) for thernioniagnetic writing. The enha nced effective coercivity was explained by the Kobayashi model, and the low er bias field and onset field of ECDL disks were analyzed by the modified n ucleation field model. The ECDL disks with magnetization over 300 emu/cm(3) , high stability and low recording bias field are potentially applicable fo r magnetic flux readout toward high density recording at a high writing rat e.