About MR sensor

Details the basic MR and GMR read structure. For MR sensor, constant current through the nickel/iron ( 镍铁) Alloy membrane, a magnetic field in the material. Soft magnetic alloy as the sensor to the disk magnetized area, magnetized regions of the new results of magnetic field in magnetic field direction change of NiFe membrane, produce voltage change. As shown, the voltage disk magnetic field change is non-linear, and design an electronic system to explain the magnetic signals will be very difficult. However, by putting a layer of magnetic soft membrane in with NiFe close to MR membrane, but separated by the direction of the high content from its iFe and magnetization of NiFe keep near the 45 ° voltage change is linear, and yes. Marked as SAL ( Soft adjacent layers) The structure is the foundation industry most of the MR head. Sense amplifier and data channel design 12 data area density projection the evolution of the head. Using SAL MR head of HDD can be used. With the continuous increase of surface density, MR head voltage change, will eventually lead to lower signal amplitude. This decline occurred in near 5 gigabits per square inch. A new sensor design, GMR head of voltage changed under the surface density of signal amplitude five gigabit / 2 inches. In GMR sensor, the two separated by a thin film of conductive gasket can provide response to voltage change of the magnetic disk. GMR sensor using the electron, and follow the principle of conduction electron spin direction parallel to the direction of the magnetic film can pass structure, do not produce voltage change.