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Rear End Bias Layer for Flux Guided Tunnel Valve Disclosure Number: IPCOM000014382D
Original Publication Date: 2001-Mar-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue



A high coercivity ferromagnetic layer is placed contiguously with the free layer at the rear end of the Tunnel Valve sensor. This layer is also insulated from the sensor so that this layer does not shunt any current flowing perpendicular to the plane of Tunnel Valve layers. This high coercivity layer is magnetized so that the magnetization is perpendicular to the boundary between the sensor and this layer. The direction of the magnetization of the high coercivity layer is selected so that its magnetic field adds to the magnetic field from the pinned layer of the sensor at the free layer location. For the Tunnel valve using antiparallel pinning for the pinned layer, the direction of the setting field for the high coercivity layer is the same as for the pinned layer. The high coercivity layer provides bias to the free layer so that the sum of the bias from the high coercivity layer (Hb) , the demagnetizing field from the pinned layer (Hd) and the ferromagnetic coupling field (Hfc) at the free layer cancels (Hfc+ Hb Hd= 0). The use of Hb field allows Hd to be smaller implying very thin pinned layer required for strong exchange pinning. 1