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Tunnel Valve Head Without Antiferromagnetic Pinning Disclosure Number: IPCOM000014111D
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue



Tunnel valve sensor operates using a pinned ferromagnetic layer (pinned by exchange coupling with the antiferromagnetic layer) and a free ferromagnetic layer separated by a thin insulating (e.g., Al2O3) tunneling barrier. The current flows perpendicular to the plane of the layers and usually the ferromagnetic shields also act as the electrodes for the head. Disclosed is a new structure to provide pinning to the ferromagnetic layer. A conductor and an insulating layer is inserted between the ferromagnetic layer and the shield. The insulator is next to the shield and conductor next to the antiferromagnet. The conductor is shorted to the shield away from the sensor active area so that current flows parallel to the conductor plane and head air bearing surface plane. The current flowing in the conductor provides field at the ferromagnetic layer for pinning. The direction of the current flow is chosen so that its field and the antiferromagnet pinning assist each other. Using high amplitude and short duration current pulse (e.g., 8 mA high pulse for 100 ns), the antiferromagnet can be reset provided its blocking temperature is less than about 250 C. Alternatively, it may be possible to eliminate the antiferromagnet and use only the field from the current flow in conductor for pinning. 1