MAGNETIC TUNNEL JUNCTION MAGNETORESISTIVE READ HEAD WITH LONGITUDINAL AND TRANSVERSE BIAS

摘要

A MAGNETIC TUNNEL JUNCTION MAGNETORESISTIVE READ HEAD (25) HAS ONE FIXED FERROMAGNETIC LAYER (118) AND ONE GENERALLY RECTANGULARLY SHAPED SENSING FERROMAGNETIC LAYER (132) ON OPPOSITE SIDES OF THE TUNNEL BARRIER LAYER (120) , AND A BIASING FERROMAGNETIC LAYER (320) LOCATED AROUND THE SIDE EDGES (180) AND BACK EDGES (190) OF THE SENSING FERROMAGNETIC LAYER. AN ELECTRICALLY INSULATING LAYER (330, 430, 460) SEPARATES THE BIASING LAYER FROM THE EDGES OF THE SENSING LAYER. THE BIASING LAYER IS A CONTINUOUS BOUNDARY BIASING LAYER THAT HAS SIDE REGIONS (322) AND A BACK REGION (324) TO SURROUND THE THREE EDGES OF THE SENSING LAYER. WHEN THE BIASING LAYER IS A SINGLE LAYER WITH CONTIGUOUS SIDE AND BACK REGIONS ITS MAGNETIC MOMENT CAN BE SELECTED TO MAKE AN ANGLE WITH THE LONG EDGES OF THE SENSING LAYER. IN THIS MANNER THE BIASING LAYER PROVIDES BOTH A TRANSVERSE BIAS FIELD TO COMPENSATE FOR TRANSVERSE FERROMAGNETIC COUPLING AND MAGNETOSTATIC COUPLING FIELDS ACTING ON THE SENSING LAYER TO THUS PROVIDE FOR A LINEAR RESPONSE OF THE HEAD AND A LONGITUDINAL BIAS FIELD TO STABILIZE THE HEAD. THE BIASING LAYER MAY ALSO BE FORMED WITH DISCRETE SIDE REGIONS (420) AND A BACK REGION (425). THE DISCRETE SIDE REGIONS MAY HAVE A MAGNETIC MOMENT ORIENTED IN A DIFFERENT DIRECTION FROM THE MOMENT OF THE BACK REGION IN ORDER TO PROVIDE THE CORRECT COMBINATION OF TRANSVERSE AND LONGITUDINAL BIAS FIELDS. (FIGURE 9)