Curved Read Sensor: Application and Fabrication
Original Publication Date: 2002-Jan-27
Included in the Prior Art Database: 2003-Jun-19
Disclosed is the use of a curved read head in-between curved shields for thermally assisted recording (TAR) application. Another important application is that curved read head can provide improved contact with lead metallization and with the hard bias. Conventional read sensors, e.g., GMR sensors in current heads, are essentially flat design, and they are sandwiched in-between flat shields. They are quite suitable for reading bits that are essentially straight within the read width, as in current head products with the write width somewhat larger than the read width. 2 As we venture into much higher recording density, beyond 100 Gb/in, thermal decay because of the superparamagnetic effect becomes more and more of an issue. One way to mitigate this is to utilize "Thermal Assisted Recording" (TAR). A particularly attractive embodiment of TAR is based on nanoheaters at the Air-Bearing Surface (ABS), and fabricated in the vicinity of the write poles. In order to be compatible with high density recording, the nanoheater lateral dimension should be small, on the order of 100 nm, and the heating time of a point on the rotating disk should be less than the order of 10 nsec if the rotational speed is 10 m/sec. Modelling of the heated spot on the disk (Fig. 1) shows that the temperature contours on the disk are substantially curved, which means that the data bit defined by the thermal gradient along the track direction is also curved, as indicated in Fig. 2. This behavior of forming significantly curved data bit by other heating mechanism (e.g., optical near-field heating) is also existent for high density recording. However, flat read heads can be poorly suited for reading such curved data bits, because the sensor/bit overlap function is significantly worse compared to suitably-curved read heads.