Magnetic recording head with clad coil

A magnetic write head for recording data having reduced erasure caused by a magnetic field is disclosed. The magnetic write head include a main pole and a conductive coil positioned adjacent the main pole. The conductive coil is insulated from the main pole. The magnetic write head includes means for directing a magnetic field produced by the conductive coil toward the main pole.

CROSS-REFERENCE TO RELATED APPLICATION(S)

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of magnetic data storage and retrieval systems. In particular, the present invention relates to a magnetic write head having cladding on coils.

In a magnetic data storage and retrieval system, a transducing head typically includes a writer for storing magnetically-encoded information of a magnetic media and a reader for retrieving the magnetically-encoded information from the magnetic media. The reader typically consists of a bottom shield, a top shield, and a magnetoresistive sensor positioned between the bottom and top shields.

The writer typically consists of a main pole and a return pole, which are separated from each other at an air bearing surface (ABS) of the writer by a gap layer, and which are connected to each other at a region distal from the air bearing surface by a back gap closer or back via. Positioned at least partially between the main and return poles are one or more layers of conductive coils, which are encapsulated by insulating layers or a writer core. The writer and the reader may be arranged in a merged configuration in which a shared pole serves as both the top shield in the reader and the return pole in the writer.

To write data to the magnetic media, an electrical current is caused to flow through the conductive coils to induce a magnetic field across the write gap between the main and return pole. By reversing the direction of the current through the coil, the polarity of the data written to the magnetic media is reversed. Because the main pole is generally the trailing pole of the main and return poles, the main pole is used to physically write the data to the magnetic media. Accordingly, it is the main pole that defines the track width of the written data. More specifically, the track width is defined by the width of the main pole at the ABS.

The current passing through the coils causes a magnetic field to generate entirely around the coils and extend from the main pole to the return pole. The magnetic field at the main pole is concentrated at the tip of the main pole and allows the main pole to write. It is important that the magnetic field is effectively delivered at the pole tip with a minimum amount of current. In particular for perpendicular writing, it is important that the magnetic field at the return pole not be strong enough to partially or completely erase information recorded on the recording medium. Thus, there is a need in the art for directing the magnetic field generated by the coils to suppress the potential for side writing and erasing caused by the magnetic field.

BRIEF SUMMARY OF THE INVENTION

The present invention is a magnetic write head for recording data having reduced erasure caused by a magnetic field. The magnetic write head includes a main pole and a conductive coil positioned adjacent the main pole. The conductive coil is insulated from the main pole. The write head includes means for directing a magnetic field produced by the conductive coil toward the main pole.

DETAILED DESCRIPTION

FIG. 1is a cross-sectional view of a prior art magnetic writer100. The magnetic writer100has a main pole102and a return pole104that are connected to one another at a back closure or via110. At an end opposite the via110, the main pole102and return pole104are separated from one another by a gap108at an air bearing surface106. Located between the main pole102and the return pole104is a conductive coil111having conductive coil turns112separated from the main pole102and return pole104by insulation114.FIG. 1shows conductive coil111arranged in a flat or pancake arrangement that spirals around the via110. Therefore, there is an equal number of coil turns at an end opposite the via (not shown).

When current passes through conductive coil turns112, a magnetic field116is generated. This magnetic field116becomes concentrated in the main pole102and causes the magnetic writer100to write to a disc. As shown inFIG. 1the magnetic field extends out the end of the main pole102and returns to the return pole104. If the magnetic field116at the return pole104is too strong, then erasure of the data can result because the magnetic field116at the return pole104is in a direction opposite to the direction of the magnetic field116at the main pole102. The present invention provides a means for directing the magnetic field116generated by the conductive coil turns112. In one embodiment the present invention provides a means for minimizing the magnetic field116at the return pole104.

FIG. 2is a cross-sectional view of a magnetic writer200having clad coils in a flat or pancake design with the other half of the coils not shown. The magnetic writer200has a main pole202and a return pole204that are connected to one another at a back closure or via210. At an opposite end from the via210, the main pole202and return pole204are separated from one another by a gap208at an air bearing surface206.FIG. 2shows the conductive coil211arranged in a flat or pancake arrangement that spirals around the via210. Located between the main pole202and the return pole204is a conductive coil211having conductive first coil turns212separated from the main pole202and return pole204by insulation214. First conductive coil turns212are shown removed from the air bearing surface206. Located at an end opposite the via210are second coil turns213.

First conductive coil turns212are surrounded by a cladding218constructed from a magnetic material. In this embodiment, the cladding218is in direct contact with the first conductive coils turns212. Bottom cladding220and side cladding222cover three sides of the first conductive coil turns212leaving an open end224to face the main pole202. The cladding218can cover only the portion of the first conductive coil turns212located between the main pole202and return pole204or can also cover the second coil turns213. In the embodiment shown inFIG. 2, second conductive coil turns are covered on all four sides with cladding219.

Because the cladding218has a much higher permeability than the surrounding material, the magnetic field generated around the conductive coil turns212,213passes preferentially through the cladding218,219. Only where the cladding is not present is the magnetic field allowed to emanate from the conductive coil turn. Open end224of first conductive coil turn212is not covered with cladding, so the magnetic field216emanates outward from open end224of the first conductive coil turns212towards the main pole202. Most of the magnetic field216is returned to the cladding218and not the return pole204because the cladding is magnetic. The cladding218decreases the strength of the magnetic field216at the return pole204, so the potential for erasure is reduced. Second conductive coil turn213is completely covered with cladding, although in different embodiments the turn could be covered on less than all sides of the turn. Completely covering the turn213with cladding219further controls the magnetic field216by not having a gap for the magnetic field to emanate out from. The magnetic field216is contained withing the cladding219.

FIG. 3is a cross-sectional view of a magnetic writer300with clad coils in a helical design. The magnetic writer300has a main pole302and a return pole304that are connected to one another at a back closure or via310. At an end opposite the via310, the main pole302and return pole304are separated from one another by a gap308at an air bearing surface306. Surrounding the main pole302in a helical design is a conductive coil311having a lower conductive coil turn312and an upper conductive coil turn313. The lower conductive coil turns312are located between the main pole302and the return pole304and the upper conductive coil turns313are located above the main pole302. The coil turns are shown as removed from the air bearing surface306. Lower conductive coil turns312and upper conductive coil turns313are insulated from the poles by insulation314.

Conductive coil turns312,313are surrounded by a cladding318constructed of a magnetic material, and in this embodiment the cladding318is in direct contact with the conductive coil turns312,313. Bottom cladding320and side cladding322cover three sides of the lower conductive coil turns312leaving an open end324of the lower conductive coil turns312facing the main pole302. Top cladding321and side cladding322cover three sides of the upper conductive coil turns313, leaving an open end324of the upper conductive coil turn313facing the main pole302. Because the cladding318has a much higher permeability than the surrounding material, the magnetic field316generated around the upper conductive coil turns313and lower conductive coil turns312passes preferentially through the cladding318. Only where the cladding318is not present is the magnetic field316allowed to emanate from the conductive coil turns312,313. Open end324of conductive coil turns312,313is not covered with the cladding318, so the magnetic field316emanates outward from open end324of the conductive coil turns312,313towards main pole302. Because the cladding318is a magnetic material, most of the magnetic field316is returned to the cladding318and not the return pole304. This decreases the strength of the magnetic field316at the return pole304, so the potential for erasure is reduced.

FIG. 4is a cross-sectional view of a magnetic writer400with clad coils in a flat or pancake design. The magnetic writer400has a main pole402and a return pole404that are connected to one another at a back closure or via410and separated from one another by a gap408at an air bearing surface406. Located between the main pole402and the return pole404is a conductive coil411having conductive coil turns412separated from the main pole402and return pole404by insulation414. The conductive coil411is arranged in a flat or pancake arrangement circling around the via410.

Conductive coil turns412are surrounded by a cladding core418. The coil turns412and cladding core418are shown as removed from the air bearing surface406but could be adjacent to the air bearing surface406. In this embodiment, the cladding is insulated from the conductive coil turns412by an insulation layer420. The insulation layer420covers three sides of the conductive coil turns412leaving open end424exposed to the main pole402. A solid cladding core418that is a continuous piece of magnetic material encloses the conductive coil turns412leaving open end424exposed to the main pole402. Because the cladding core418has a much higher permeability than the surrounding material, the magnetic field416generated around the conductive coil turns412passes preferentially through the cladding core418. Only where the cladding core418is not present is the magnetic field416allowed to emanate from the conductive coil turns412. Open end424of conductive coil turns412is not covered with the cladding core418, so the magnetic field416emanates outward from open end424of the conductive coil turns412towards the main pole402. Because the cladding core418is magnetic, most of the magnetic field416is returned to the cladding core418and not the return pole404. Minimizing the magnetic field416at the return pole404, decreases the strength of the magnetic field316at the return pole, so the potential for erasure is reduced. A cladding core418can also be provided around the coil turns located at an opposite end of the via410(not shown).

FIG. 5is a cross-sectional view of a magnetic writer500with clad coils in a flat or pancake design and a clad shield524. The magnetic writer500has a main pole502and a return pole504that are connected to one another at a back closure or via510and separated from one another by a gap508at an air bearing surface506. Located between the main pole502and the return pole504is a conductive coil511having conductive coil turns512separated from the main pole502and return pole504by insulation514. The conductive coil511is arranged in a flat or pancake pattern circling around the via510. Therefore, there are an equal number of coil turns512at an end opposite the via510(not shown).

Conductive coil turns512are surrounded by a cladding518constructed of a magnetic material. In this embodiment, the cladding518is in direct contact with the conductive coil turns512. Bottom cladding520and side cladding522cover three sides of the conductive coil turns512leaving an open end528of the conductive coil turns512exposed to the main pole502. Because the cladding518has a much higher permeability than the surrounding material, the magnetic field516generated around the conductive coil turns512passes preferentially through the cladding518. Only where the cladding518is not present is the magnetic field516allowed to emanate from the conductive coil turns512. Open end528of the conductive coil turns512is not covered with cladding518, so the magnetic field516emanates outward from open end528of the conductive coil turns512towards the main pole502. Because the cladding518is magnetic, most of the magnetic field516is returned to the cladding518and not the return pole504. In addition to the cladding518surrounding the conductive coil turns512, a cladding shield524is used to further allow the magnetic field516to pass through the cladding shield524and minimize the magnetic field518at the return pole504. The cladding shield524is also constructed of a magnetic material and may be necessary if the cladding518becomes saturated from the magnetic field516. Directing the magnetic field516through the cladding518and cladding shield524minimizes the magnetic field516at the return pole, reducing the potential for erasure. The cladding518and the cladding shield524can be provided for the conductive coil turns512at an opposite end from the via510(not shown).

FIGS. 6 and 7show a magnetic writer600with a clad coil having a single turn around a main pole.FIG. 6is a cross-sectional view taken through line6-6ofFIG. 7. The magnetic writer600has a main pole602and a air bearing surface606. Surrounding the main pole602with one turn is a conductive coil611having an upper conductive coil turn612and a lower conductive coil turn613. Upper coil turn612and lower coil turn613are shown adjacent to the air bearing surface606but could be removed from the air bearing surface606. The conductive coil turns612,613are separated from the main pole602by insulation614.

Upper conductive coil turn612is surrounded by a cladding618that is in direct contact with upper conductive coil turn612. Top cladding621and side cladding622cover three sides of the upper conductive coil turn612leaving an open end624of the upper conductive coil turn612exposed to the main pole602. Lower conductive coil turn613is surrounded by a cladding618that is in direct contact with the lower conductive coil turn613. Lower cladding620and side cladding622cover three sides of the lower conductive coil turn613leaving an open end624of the lower conductive coil turn613exposed to the main pole602. Because the cladding618has a much higher permeability, the magnetic field616generated around the upper conductive coil turn612and lower conductive coil turn613passes preferentially through the cladding618. Only where the cladding618is not present is the magnetic field616allowed to emanate from the conductive coil turn612,613. Open end624of the conductive coil turn612,613is not covered with the cladding618, so the magnetic field616emanates outward from open end624of the conductive coil turns612,613towards the main pole602.

In this embodiment, there is not a return pole and because the cladding618is constructed of a magnetic material, most of the magnetic field616is returned to the cladding618. To prevent erasure problem with the magnetic field616returning to the cladding618, the cladding618can be designed so as to saturate during the write process. This will prevent the return magnetic field from going through the cladding. Then, the magnetic field616will propagate through a larger volume of non-permeable material around the writer600. Alternatively, the cladding618and conductive coil turns612,613can be recessed from the air bearing surface606to minimize erasure caused by the return magnetic field616.

FIG. 7is a top view of the writer shown inFIG. 6. As can be seen the writer600is a U-shaped device with one end shown shown broken626that extends to make the electrical connection to the coil and the other end closed630. At the closed end630the upper and lower conductive coil turns meet at a via628. The U-shaped device curves at the air bearing surface606. Extending from the writer600at the air bearing surface606is the main pole602. Surrounding the main pole are the clad coils618.

The embodiment shown inFIGS. 6 and 7has the advantage that its overall size is reduced, thereby reducing writer volume and improving high data rate performance. The return pole has been eliminated, there is only one turn of the conductive coil611, and the overall length of the main pole602is reduced. All of these features lead to a decreased size of the writer600.

The conductive coils of the present invention are constructed of a non-magnetic, conductive material having a low resistivity such as copper. The cladding, cladding core, and cladding shield are made of magnetically soft, permeable material. The material may be a magnetically soft alloy or a soft ferromagnetic alloy. Such materials for the cladding may include Ni80Fe20,CoZrTa, CoZrNb, CoNiFe, FeAlN, or NiFeCu. The permeable material allows for the magnetic field to pass through the material and extend out only where the permeable material is missing. Further the magnetic field passing through the cladding, cladding core, and cladding shield is added to the magnetic field generated by the current passing through the conductive coil.

In the embodiments described the main pole may be constructed of a single layer of material or may be constructed of a double layer structure. For the double layer structure, one layer may be a soft material that is slightly recessed from the air bearing surface while the other layer at the air bearing surface is a high coercivity material. The double layer material has advantages for high frequency writing that is known in the art.

The cladding, cladding core and cladding shield allow for better direction of the magnetic field generated through the conductive coils by focusing the magnetic field at the main pole and reducing the field at a return pole. This allow for increased focus of the magnetic field at the main pole allowing for a minimum amount of current. This focused magnetic field also allows the return pole to be positioned closer to the main pole.

In other embodiments of the present invention, the cladding or cladding core may be formed on all four sides of the coil turns or less than four sides of the conductive coil turns. It may be desirable to focus the magnetic field on the main pole and the return pole, thus leaving the sides of the conductive coil turns facing the poles free of cladding material. Cladding material may be formed on only one side of the conductive coil turn, preferably the side of the conductive coil turn facing the return pole to minimize magnetic field at the return pole. If there is not a return pole in the design, then the cladding material best directs the magnetic field to the main pole when no cladding is present on the side of the coil facing the main pole.

The cladding, cladding core, or cladding shield can be formed uniformly along the full length of the conductive coil. In other embodiments, the cladding, cladding core, or cladding shield can be formed nonuniformly along the length of the conductive coil. When it is formed nonuniformly, the cladding, cladding core, or cladding shield may be only in the region closely adjacent to the main pole. Additionally, the cladding, cladding core, or cladding shield may be formed in the region located outside of the main pole area, behind the via. In such a situation, the cladding, cladding core or cladding shield may be formed the same or differently than the cladding at the main pole area. In one embodiment, the cladding may be formed on all four sides of the conductive coil in the area outside of the main pole as shown inFIG. 2.

Reducing the magnetic field at the return pole reduces the potential for side erasure. Additionally, because the cladding, cladding core, and cladding shield allows for better direction of the magnetic field, the conductive coils may be placed closer to the air bearing surface to increase writer efficiency without having magnetic field leaking to the medium and interfering with the writing process. In some embodiments, the cladding, cladding core, or cladding shield may be positioned at the air bearing surface, or the cladding, cladding core, or cladding shield may be removed from the air bearing surface.

A cladding, cladding core, and cladding shield can dissipate heat generated from the current through the conductive coils more effectively than insulation alone. Therefore, the present invention can have the effect of reducing localized heating within the write head.

Cladding may be formed in a manner to affect an oriented magnetic anisotropy in order to control the permeability and the domain structure of the cladding. An induced anisotropy helps prevent a magnetic field from interfering with the medium when the writer is not in operation. Therefore, an induced anisotropy helps prevent erasure problems caused by the cladding.

AlthoughFIG. 2-6depict the cladding as a single layer, the cladding may be a multiple layer structure having an additional bias layer such as an antiferromagnetic exchange layer, which also may control the cladding permeability and domain structure. An antiferromagnetic exchange layer would be placed in contact with the cladding layer.

Cladding anisotropy and magnetization can be controlled in such a manner to effect frequency response of permeability. The cladding may be fabricated of suitable thickness, anisotropy, and magnetization to either saturate or to not saturate during operation. Further, cladding can be used to improve high data performance by reducing inductance.

As is apparent from the disclosure of the invention, any design of coils such as flat or helical may be used to carry out the present invention. Additionally, although the present invention is primarily directed at perpendicular recording, the design may also apply to longitudinal recording as well.

In constructing the clad coils for a write head of the present invention as shown inFIG. 2, on top of the return pole and a layer of insulation, a seed layer of a magnetic material is deposited that will form the bottom clad220. On the magnetic seed layer, conductive coil211is plated. The cladding218is deposited as a magnetic film over the entire surface. The magnetic film and magnetic seed layer is milled from the area between the conductive coil211leaving magnetic film to form the side cladding222and bottom cladding220. The top surface of the conductive coil211is planarized removing the top layer of the magnetic film and exposing open end224. Insulation is filled in to cover the conductive coil211, and then through chemical mechanical polishing the insulation is planarized to a flat surface. A layer of alumina insulation is covered on the insulation, and then the main pole202is deposited. A similar process with variations to conform to the particular aspects of each embodiment can be used to construct the write heads of the various embodiments of the present invention.