Side shield pedestal for data readers

Various embodiments may be generally directed to a magnetic element capable of reading magnetic data bits. Such a magnetic element may have at least a magnetic stack laterally adjacent a side shield and non-magnetic pedestal on an air bearing surface (ABS). The non-magnetic pedestal can be configured to have a greater stripe height from the ABS than the side shield.

SUMMARY

Various embodiments are generally directed to a data reader capable of magnetic data bit sensing.

In accordance with some embodiments, a magnetic stack may be laterally adjacent a side shield and non-magnetic pedestal on an air bearing surface (ABS). The non-magnetic pedestal can have a greater stripe height from the ABS than the side shield.

DETAILED DESCRIPTION

As data storage devices push towards larger capacity, faster data storage devices, and greater data reliability, the magnetic operation of various data access component has been stressed. One such data storage element is a magnetic data reader, which can be sensitive to magnetic volatility that magnetic shields are designed to mitigate. However, the physical minimization of magnetic shields has brought shielded magnetic flux in closer proximity to the magnetically responsive portions of the data reader that consequently degrades the magnetic performance and reliability of the data reader. Hence, reduced form factor magnetic shields capable of maintaining magnetic stability while shielding magnetic flux and providing magnetic bias to magnetically sensitive portions of the data reader have been a continued goal for the data storage industry.

Accordingly, a magnetic reader may be configured at least with a magnetic stack positioned laterally adjacent a side shield and non-magnetic pedestal on an air bearing surface (ABS) with the non-magnetic pedestal having a greater stripe height from the ABS than the side shield. The ability to tune the thickness of the pedestal and the stripe height of the side shield provides reduced magnetic field bias on the magnetic stack by decreasing the amount of soft magnetic material in the side shields by making them thinner. As such, the pedestal and side shield can be configured to provide predetermined magnetic bias to the magnetic stack that is balanced against the magnetic stability of the side shield, which allows the magnetic element can be catered to the diverse shielding environments provided by reduced form factor, high data bit density data storage devices.

FIG. 1generally provides an exemplary data storage environment in which magnetic shielding can be tuned in accordance with various embodiments. While not required or limiting, the data storage environment has a data transducing portion100that is configured with an actuating assembly102that positions a transducing head104over programmed data bits106present on a magnetic storage media108that is attached to, and rotates about, a spindle motor110to produce an air bearing surface (ABS)112. The speed in which the spindle motor110rotates allows a slider portion114of the actuating assembly102to fly on the ABS112to position a head gimbal assembly (HGA)116, which includes the transducing head104, over a desired portion of the media108.

The transducing head104may be constructed with one or more transducing elements, such as a magnetic writer and magnetically responsive reader, which operate to program data to and read data bits106from the storage media108, respectively. In this way, controlled motion of the actuating assembly102and spindle motor110can modulate the position of the transducing head104both laterally along predetermined data tracks118defined on the storage media surface120and vertically as measured perpendicularly to the media surface120across the ABS112to selectively write, read, and rewrite data.

FIG. 2shows an ABS view block representation of an example magnetic element130capable of being used in the transducing portion100of a data storage device shown inFIG. 1. The magnetic element130may be configured with an unlimited variety of materials, layers, and orientations that are capable of data bit sensing, but in the embodiment shown inFIG. 2, a magnetic stack132is disposed between and separated from magnetic side shields134on the ABS. The magnetic stack132is configured as an abutted junction lamination characterized by a fixed magnetization provided by a pinning layer136, such as an antiferromagnetic material, contacting a reference layer138via a coupling layer139that may create a synthetic antiferromagnet with the pinning136, reference138, and coupling139layers. The reference layer is positioned opposite a barrier layer140from a magnetically free layer142, but the barrier layer140may be configured to be a non-magnetic spacer layer in various embodiments.

It should be noted that the term “stack” is an unlimited term within this disclosure that can be one or more vertically and horizontally aligned layers, constructed of magnetic and non-magnetic material that are capable of magnetic reading and writing. Throughout the present application, the term “stack” will be understood to mean a component that is constructed to respond to external data bits to provide access to external data bits in any operational environment. For example, but not in any way limiting, a magnetic stack may be a data read or write configuration that can differentiate between a plurality of data bits.

In some embodiments, the magnetic stack132can be constructed as a trilayer lamination that has no fixed magnetization, but instead two magnetically free layers biased to a default magnetization by an external biasing structure, such as a rear bias magnet or the side shields134. Regardless of the configuration of the magnetic stack132, the emphasis on reducing the shield-to-shield spacing144between the leading146and trailing148shields has reduced the thickness of the insulator layer150that buffers shielded magnetic flux in the side shields134from inadvertently influencing the magnetic stack132. Specifically, the presence of soft magnetic side shield134materials, like NiFe, can saturate with shielded magnetic fields that can rotate abruptly and in directions opposed to the sensed magnetization of the stack free layer142, which can lead to data reading errors and increased magnetic element130latency.

With these operational challenges in mind, the amount of soft magnetic material in the side shields134can be minimized to provide a balance between magnetic shielding, magnetic stack bias magnitude, and magnetic element130stability.FIG. 3displays an ABS view block representation of a portion of an example magnetic reader150tuned in accordance with some embodiments to provide enough magnetic stack bias with magnetically stable shielding. As shown, each lateral side shield154has a thickness156that is reduced compared to the side shield134ofFIG. 2by the thickness158of a non-magnetic pedestal160.

The respective thicknesses156and158of the side shield154and pedestal160can be tuned so that magnetic material continuously extends from a trailing shield162towards the leading shield164. Various embodiments extend the side shield thickness156to be greater than the thickness of the magnetically free layer166of the magnetic stack152, but less than the aggregate thickness of the free layer166and barrier layer168from the trailing shield162. The side shields154can be configured in other embodiments to continuously extend beyond the barrier layer168to be laterally adjacent the pinned170and pinning172layers of the magnetic stack152.

The variable thickness of the side shields154, and consequently the non-magnetic pedestal160, provides the ability to have more, or less, magnetic bias magnetization provided to the magnetic stack152at the ABS. With the side shield thickness156shown inFIG. 3that extends to no farther than the barrier layer168, the soft magnetic material of the side shields154are positioned to shield magnetic flux from the magnetically sensitive free layer166while providing magnetic bias primarily to the free layer166. Along those lines, the tuned side shield thickness156can, in some embodiments, correspond with a heightened pinning layer172thickness and magnetic strength to fend off errant magnetic fields present due to lack of shielding material below the barrier layer168.

The tuning of the side shields154and pedestal160is not limited to their respective configurations at the ABS.FIG. 4is a top view block representation of a magnetic element180that illustrates how the stripe heights of the magnetic shields182and magnetic stack184can be tuned in accordance with various embodiments. The top view ofFIG. 4shows how soft magnetic material of the side shield182can be replaced with non-magnetic spacers190that fill in the difference between the stripe heights186and188, as measured from the ABS along the Z axis, of the side shield182and magnetic stack184. That is, the non-magnetic material of the pedestal present on the ABS can continuously or discontinuously extend from the ABS to behind the side shields182to localize the soft magnetic material of the side shields182to the ABS.

With the soft magnetic side shields182being minimized about the ABS and the free layer of the magnetic stack, as displayed inFIG. 3, the chance of shielded magnetic fields adversely influencing data sensing operation in the magnetic stack184is greatly reduced. However, such minimal shielding may not adequately define the magnetic extent of the magnetic stack184to be able to reliably read individual data bits, especially data bits densely packed into a high areal density. In other words, the minimal side shields182inFIG. 4may not be enough to prevent the magnetic stack184from inadvertently sensing data bits from adjacent data tracks, which can result in increased noise and reduced magnetoresistive ratio for the magnetic stack184.

FIG. 5is a cross-sectional block representation of an example data reader200tuned in accordance with some embodiments to reduce the amount of soft magnetic material proximal the magnetically sensitive portions of the data reader200while providing an increased level of magnetic shielding compared to the configuration of element180ofFIG. 4. The side shield202is configured with a head portion204at the ABS and a tail portion206continuously extending from the head portion204along the Z axis. The head204and tail206portions can be respectively tuned for thickness to provide a balance between magnetic bias being provided to the adjacent magnetic stack and side shield202stabilization.

In comparison to the tuned magnetic element180ofFIG. 4where the side shields182extended no farther than stripe height186, configuring the side shield202with the increased thickness head portion204at the ABS and the reduced thickness tail portion distal to the ABS allows for magnetic shielding along some, or all, of the stripe height of the magnetic stack while decreasing the risk that the tail portion will saturate and inadvertently influence operation of the adjacent magnetic stack. The reduced thickness of the tail portion204along the Y axis, parallel to the ABS, further allows the side shield202to be buffered by an increased amount of non-magnetic material as the non-magnetic pedestal208and non-magnetic spacer210contact the side shield202on opposite sides. The reduced thickness of the tail portion204may also exert less magnetic torque on the magnetic stack, particularly the reference layer, to make the magnetic stack more stable and provide optimized magnetic asymmetry operation.

Just as the tail portion206of the side shield202can be uniquely tuned, the head portion204may be tuned with a shaped rear wall212, distal the ABS, that can allow for more efficient flow of magnetization between the head202and tail204portions. That is, the rear wall212can be tuned with an unlimited variety of shapes, such as the linear surface tapered at a predetermined angle θ1or a continuously curvilinear surface, to minimize the amount of magnetic domains in the side shield202and reduce the chance that retained magnetization in the side shield202can influence the magnetic stack.

With the moderate and tuned increase in magnetic material in data reader200, along with leading214and trailing216shields, magnetic stabilization can be more robust in the face of heightened levels of magnetic flux present in modern, high data bit density data storage devices. The ability to tune the shape, stripe height, and thickness of the pedestal208and side shield202can allow for considerably different magnetic shielding characteristics that can be conducive to a wide variety of different data storage environments.

FIG. 6plots operational data from example data readers tuned with different side shield head and tail portion thicknesses at the ABS. The first cross-hatching shown in column222and found for each different data reader configurations, corresponds with the Y axis aligned magnetization of the side shield in the presence of zero magnetic field along the Y axis. The second cross-hatching of column224and the other data reader configurations illustrates the Y axis aligned magnetization amplitude for the side shield. Finally, the third cross-hatching found in each data reader configuration and specifically column226shows the derivative Y axis magnetization amplitude for the side shield.

As can be appreciated from the different transverse magnetization readings for the respective head and tail portion thicknesses, a thicker tail portion corresponds with greater transverse magnetization that may be attributed to the increased amount of soft magnetic material adjacent the magnetic stack. In contrast, tuning the tail portion of the side shield to be thinner, or eliminated, can provide different, but optimized data reader static and dynamic metrics that support the balance of magnetic shielding with magnetic stability.

FIG. 7provides an example flowchart of a data reader fabrication routine240that maps how a magnetic element can be tuned in accordance with various embodiments. The routine240may begin with the deposition of a leading shield on a substrate in step242. Next, step244forms a non-magnetic pedestal with a predetermined thickness on the bottom shield. The pedestal may be configured as a single layer, such as Ta, Ru, or AlO, or as a lamination of similar or dissimilar materials. The formation of the non-magnetic pedestal is followed by step246where a soft magnetic side shield is deposited with a stripe height to match the magnetic stack, regardless of whether the magnetic stack has been formed yet or not.

With the side shield extending the full stripe height of the data reader with a continuous and uniform predetermined thickness, decision248evaluates and determines if the side shield is to have a tail portion, such as the tail206shown inFIG. 5. If indeed a tail portion is to be constructed, step250reduces the thickness of a predetermined portion of the side shield, distal the ABS. In some embodiments, step250further shapes a rear wall of the head portion of the side shield. A determination in decision248that no tail portion is desired advances routine240to step252where a predetermined amount of the side shield stripe height distal to the ABS is removed. Similarly to step250, step252may also shape a rear wall of the remaining side shield during or after the removal of the side shield material.

Step254then forms a non-magnetic spacer layer atop the side shield in the event a tail portion is present or atop the pedestal if the side shield is localized to the ABS. The non-magnetic spacer layer may be formed of an unlimited variety of materials, such as Ta and AlO, with any deposition process, such as sputtering, atomic layer deposition, and vapor deposition. The completion of the side shields with step254can be immediately followed by step256where the magnetic stack is deposited between the side shields. As can be appreciated, the magnetic stack can comprise a number of different layers, deposition techniques, and materials, such as with abutted junction and trilayer laminations.

The routine may conclude with step258, which forms a trailing shield that continuously spans each side shield, non-magnetic spacer layer, and the magnetic stack to finalize the data reader. With the ability to tune the various side shield and pedestal layers, the magnetic operation of the magnetic stack can be optimized for a variety of data storage environments. The routine240, however, is not limited only to the steps and decisions provided inFIG. 7as any number of steps can be added, omitted, and modified to accommodate the fabrication of a precisely tuned magnetic reader. For instance, the deposition of the magnetic stack can be conducted prior to step244or conducted concurrently with some or all of the deposition of the side shields.

It can be appreciated that a tuned side shield and non-magnetic pedestal configuration can provide diverse balance between magnetic stabilization and shielding of a magnetic stack. Through the tuning of the thickness, stripe height, and material of the pedestal and side shield, a variety of magnetic stack operating parameters can be optimized. Moreover, the ability to tune the side shield to have a tail portion that extends to match the stripe height of the magnetic stack with a reduced thickness can be tuned to minimize the amount of soft magnetic material proximal the magnetic stack while providing reliable magnetic shielding in reduced form factor, high data bit density data storage environments. Additionally, while the embodiments have been directed to magnetic sensing, it will be appreciated that the claimed invention can readily be utilized in any number of other applications, including data storage device applications.