Patent ID: 9601138
Date: 2017-03-21
CPC Classifications: G11B

Claim:
1. A TDMR (two dimensional magnetic recording) read head having longitudinally biased freelayers with unidirectional anisotropy in a longitudinal direction, comprising: a top sensor top shield; a patterned top sensor placed beneath and contiguous with said top sensor top shield, wherein said patterned top sensor includes a freelayer having a unidirectional magnetic anisotropy aligned in a horizontal direction; a top sensor bottom shield; a non-magnetic spacer layer; a bottom sensor top shield; a patterned bottom sensor placed beneath and contiguous with said bottom sensor top shield, wherein said patterned bottom sensor includes a freelayer having a unidirectional magnetic anisotropy aligned in a horizontal direction; a bottom sensor bottom shield; wherein said top and bottom sensors are identical in pattern and structure and symmetrically positioned; and an oppositely disposed pair of soft magnetic biasing layers or a multilayer of soft magnetic biasing layers that symmetrically abut patterned lateral sides of each said identically patterned sensor thereby stably biasing each said freelayer therein and producing said unidirectional magnetic anisotropy in each said freelayer therein; and a pair of symmetrically formed antiferromagnetic layers exchange coupled to said soft magnetic biasing layers or said multilayer of soft magnetic biasing layers in each said sensor, thereby stabilizing said biasing of each said freelayer therein; and wherein said top sensor top shield is also biased in the same direction as said freelayer in said top sensor and wherein said bottom sensor top shield is also biased in the same direction as said freelayer in said bottom sensor and wherein both said top shield of said top sensor and said top shield of said bottom sensor are exchange coupled to said pair of antiferromagnetic layers of their respective sensors and are also provided with a stabilized unidirectional magnetic anisotropy thereby.