ANTIFERROMAGNETIC AND HARD-MAGNETIC STABILIZATION SCHEMES FOR MAGNETORESISTIVE SENSORS

Antiferromagnetic Ni-Mn and hard-magnetic Co-Pt-Cr stabilization schem es for magnetoresistive (MR) sensors are evaluated in this paper. Magn etic properties of Ni-Fe (bottom)/Ni-Mn(top), Ni-Mn/Ni-Fe, Co-Pt-Cr, N i-Fe/Co-Pt-Cr and Co-Pt-Cr/Ni-Fe films used in various types of MR sen sors are characterized, and the read performance of two types of MR se nsors, one overlaid with a Ni-Mn film in tail regions and. the other a butted with a Co-Pt-Cr film, is then studied. In the Si-Mn stabilizati on scheme, the unidirectional anisotropy field of the Ni-Fe/Ni-Mn film s increases when the MR sensor is thinner, and the MR responses are qu iet and stable. In the Co-Pt-Cr stabilization scheme, the remanence ma gnetic moment and coercivity of the Co-Pt-Cr film decrease when the fi lm is thinner, and the MR responses are quiet and stable when the magn etic moment of the Co-Pt-Cr film is higher than that of the MR film. T his magnetic moment cannot be very high to prevent the reduction of se nsor sensitivity and effective readwidth. To select a suitable stabili zation scheme for thinner MR sensors, simplicity in sensor magnetics a nd fabrication should also be considered.