Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Thomas Hauet

Olav Hellwig

Lidu Huang

Manfred Ernst Schabes

Kentaro Takano

A patterned perpendicular magnetic recording medium, such as a disk for use in hard disk drives, has a flux channeling layer (FCL) located below the recording layer (RL) in each of the discrete data islands. The disk includes a substrate, a soft underlayer (SUL) of soft magnetically permeable material on the substrate, and a nonmagnetic exchange break layer (EBL) on the SUL. A nonmagnetic separation layer (SL) is located between the FCL and the RL in the islands. The FCL has an anisotropy field substantially lower than the anisotropy field of the RL, and a magnetization equal to or higher than the magnetization of the RL. The FCL is saturated at a much lower field than the RL and thus channels the magnetic flux from the write head through the island positions. The dipolar fields from the RL above the FCL polarize the magnetization of the FCL parallel to the magnetization direction of the RL in the absence of an external field, to thereby enhance the readback signal.

Patterned perpendicular magnetic recording medium with data islands having a flux channeling layer below the recording layer

Multiple anisotropy layered magnetic structures for controlling reversal mechanism and tightening of switching field distribution in bit patterned media are disclosed. The invention extends the exchange spring concept to more variable and sophisticated structures. Three or more layers with different anisotropy or anisotropy gradients increase writeability gains beyond the simple hard/soft bilayer exchange spring concept for BPM. The structures have a thin very hard, high anisotropy center layer that acts as a threshold or pinning layer for domain wall propagation through the entire media structure. In addition or alternatively, a thin very soft, low anisotropy center layer in between the commonly used soft surface layer and hard media layer allows quick initial propagation of the domain wall into the center of the media structure. Various properties of the media structures can be tuned more independently for optimization if using more advanced multi-anisotropy layer stacks.

System, method and apparatus for multiple anisotropy layered magnetic structures for controlling reversal mechanism and tightening of switching field distribution in bit patterned media

Multilayer magnetic structures control the switching field and tighten the switching field distribution in bit patterned media. A strain-inducing layer is excited, e.g., by a localized magnetic field or a localized thermal heating or a voltage, and induces a strain on the magnetic layer(s) of the patterned bit to initiate switching of the bit magnetization. The strain induced on the magnetic layer forces a rotation or an amplitude variation of the magnetic layer anisotropy. A localized magnetic field is simultaneously or subsequently applied to complete the switching of the bit magnetization. The invention provides control of switching field and switching field distribution for bit-patterned media devices.

System, method and apparatus for strain-assisted magnetic recording for controlling switching field and tightening switching field distribution in bit patterned media

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Thomas Hauet