CPP GMR/TV IN DIFFERENTIAL MODE
Original Publication Date: 2002-Nov-14
Included in the Prior Art Database: 2002-Nov-14
The CPP GMR or Tunnel Valve sensor disclosed here functions as a differential sensor with common SELF-PINNED layers also serving as the common electrode for this sensor. This sensor rejects common mode noise while the signals from the two sensors are added. The common self-pinned layer is AP-Coupled (CoFe/Ru/CoFe) where 180 degree out of phase magnetizations of the two CoFe layers provide 180 degree out of phase signals which are added in differential detection while commom mode noise (e.g. noise from thermal asperity or sensor heating) is rejected. The self-pinning is achieved by providing large positive magnetostriction of CoFe layers (E.g. Co60Fe40 alloy provides large positive magnetostriction) together with the compressive stress at the air bearing surface. This combination generates magnetic easy axis perpendicular to the air bearing surface for the pinned layers.