Flux-guided tunneling magnetoresistive (TMR) sensor for magnetic tape with reduced likelihood of electrical shorting

Abstract

A tunneling magnetoresistive (TMR) read head for magnetic tape has a tape-bearing surface (TBS) and includes a first magnetic shield, a first gap layer on the first shield, a TMR sensor on the first gap layer and recessed from the TBS, a second gap layer on the TMR sensor, a second magnetic shield on the second gap layer, and a magnetic flux guide between the first and second gap layers between the TBS and the recessed TMR sensor. The first gap layer has an insulating portion with an edge at the TBS and a non-magnetic electrically-conducting portion recessed from the TBS, with the TMR sensor located on the conductive portion. The sense current is between the two shields. An insulating isolation layer may be located between the first gap layer and the first shield layer with the sense current being between the second shield and the first gap layer.

Description

BACKGROUND OF THE INVENTIONField of the Invention[0001]The invention relates generally to a read head for magnetic tape, and more particularly to a tunneling magnetoresistive (TMR) type of read head with a flux guide for directing magnetic flux from the magnetic tape to the TMR sensor.Background of the Invention[0002]One proposed type of magnetoresistive sensor used as the read head in magnetic recording tape drives is a magnetic tunnel junction sensor, also called a tunneling MR or TMR sensor. A TMR sensor has a stack of layers that includes two ferromagnetic layers separated by a tunneling barrier layer, i.e., a nonmagnetic electrically insulating spacer layer, which is typically MgO. One ferromagnetic layer adjacent the tunneling barrier layer has its magnetization direction fixed, such as by being pinned by exchange coupling with an adjacent antiferromagnetic layer, and is referred to as the reference layer. The other ferromagnetic layer adjacent the tunneling barrier layer has ...

AI Technical Summary

Benefits of technology

[0007]In a first embodiment the first gap layer has a non-electrically-conducting portion with an edge at the TBS and a non-magnetic electrically-conducting portion recessed from the TBS, with the TMR sensor being located on the conductive portion recessed from the TBS. The sense current is between the first and second shield layers through the TMR sensor. Because there is no electrically-conductive gap material at the TBS between the flux guide and the first shield layer, and because the non-electrically-conducting portion of the first gap layer at the TBS provides increased separation between the edge of the flux guide and the first shield layer, there is less likelihood that a scratch at the TBS will create a conductive bridge between the flux guide and the first shield layer, which would short the sense current.

[0008]In a second embodiment an insulating isolation layer is located between the first gap layer and the first shield layer. The sense current is between the second shield layer and the first gap layer through the TMR sensor and does not pass through the first shield layer. The first and second shield layers can be connected in a region behind the TMR sensor so that they are at the same electrical potential. Thus even if a scratch at the TBS were to cause conductive material from the first shield layer to bridge the isolation layer and the insulating portion of the first gap layer, there would be no shorting of the sense current because the sense current is between the conductive portion the first gap layer and the second shield layer. An optional protective overcoat may be formed on the TBS in both embodiments. However, an overcoat is undesirable because it increases the spacing between the edge of the flux guide and the magnetic tape. The second embodiment provides the additional advantage that eliminates the need for an overcoat on the TBS because a scratch at the TBS will not cause shorting of the sense current.

Problems solved by technology

However, an overcoat is undesirable because it increases the spacing between the edge of the flux guide and the magnetic tape.

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