Abstract: A magnetic head includes a first shielding layer, a second shielding layer, an MR element, and a marker layer. The layers and the element are exposed from a medium sliding surface while being inclined at an azimuth angle. A major part of the marker layer is disposed inside two imaginary azimuth lines, which extend straight in one direction through both end portions in the track-width direction of the MR element, in the track-width direction, and both end portions thereof are disposed outside the imaginary azimuth lines in the track-width direction. In the magnetic head, the MR height can be precisely controlled, and changes in asymmetry are reduced.

Abstract: Provided are a thin film magnetic head capable of inhibiting an excessive temperature rise while reducing its size in accordance with a higher recording density, and obtaining a higher read output, a method of manufacturing the same, and a magnetic disk drive using the thin film magnetic head. A heat dissipation layer for transferring heat generated in a magnetic transducer film to outside is disposed adjacent to the magnetic transducer film on a side, the side being opposite to a side facing a recording medium. In a gap layer for electrically insulating between the magnetic transducer film and a pair of shield layers, a portion of the gap layer in contact with an end surface of the magnetic transducer film on a side, the side being opposite to a side facing the recording medium is formed so as to have a thin thickness ranging from 2 nm to 30 nm inclusive.

Abstract: Provided are a thin film magnetic head capable of inhibiting an excessive temperature rise while reducing its size in accordance with a higher recording density, and obtaining a higher read output, a method of manufacturing the same, and a magnetic disk drive using the thin film magnetic head. A heat dissipation layer for transferring heat generated in a magnetic transducer film to outside is disposed adjacent to the magnetic transducer film on a side, the side being opposite to a side facing a recording medium. In a gap layer for electrically insulating between the magnetic transducer film and a pair of shield layers, a portion of the gap layer in contact with an end surface of the magnetic transducer film on a side, the side being opposite to a side facing the recording medium is formed so as to have a thin thickness ranging from 2 nm to 30 nm inclusive.

Abstract: In a spin value type transducer including two magnetic shield layers, a patterned magnetoresistance element is in direct contact with one of the magnetic shield layers. A permanent magnet layer and an electrode layer are formed on the sides of the patterned magnetoresistance element.

Abstract: A reader formed in a data transducer includes a first shield, a read gap, a second shield, a maanetic compensation layer, and a non-magnetic spacer layer. The first shield is formed of a multilayer comprised of a layer of a first material. The second shield is spaced apart from the first shield by the read gap. The magnetic compensation layer is formed in the first shield and has a coefficient of thermal expansion of less than the coefficient of thermal expansion of the first material. The non-magnetic spacer layer separates the first material layer and the compensation layer of the first shield.

Abstract: A magnetic recording disk drive has a disk with the magnetizations in the concentric data tracks oriented in the cross-track direction. The concentric data tracks are magnetically separated from each other by guard bands. An inductive write head has its write poles and write gap oriented to generate magnetic fields in the cross-track direction. The guard bands may provide magnetic separation by containing along-the-track magnetizations, in which case the write head also has an erase pole and an erase gap to generate magnetic fields in an along-the-track direction on the sides of the data tracks. A magnetoresistive read head has its free-layer magnetization direction perpendicular to the disk surface and its pinned-layer magnetization direction parallel to the disk surface and orthogonal to the free-layer magnetization direction. The read head may have magnetic side shields spaced from it in the cross-track direction to prevent magnetic flux from adjacent data tracks from reaching the read head.

Abstract: In a spin value type transducer including two magnetic shield layers, a patterned magnetoresistance element is in direct contact with one of the magnetic shield layers. A permanent magnet layer and an electrode layer are formed on the sides of the patterned magnetoresistance element.

Abstract: Increases in the AP1 and AP2 thickness cause the free layer to be off-center in a CPP magnetic read head. This problem has been overcome by inserting supplementary magnetic shields within the spin valve, located as close as possible to the stack. These supplementary shields enable the read gap width to be reduced by about 430 ? and the free layer to shift back towards the center by about 30 ?.

Abstract: The invention presents techniques for verifying patterns, such as time-based servo marks, recorded on magnetic media. Patterns of this kind can be recorded on a magnetic medium using a recording head that includes a surface having a flux gap with a defined shape. The patterns may be verified with a verify head, having a surface with a flux gap with the defined shape or part of the defined shape. The verify head may include two or more ferromagnetic cores, with a flux gap associated with each core. Each core can independently verify part of the recorded pattern.

Abstract: A magnetic material having a low coefficient of thermal expansion of 11.5×10?6/K or less is used for forming at least one of a lower shield or an upper shield. A laminated film comprising a layer of the magnetic material having a low coefficient of thermal expansion of 11.5×10?6/K or less, and an 80 wt % NiFe alloy layer, is used for forming at least one of the lower shield and the upper shield. Thus, the thin film magnetic head having reduced after-record noise and reduced thermal protrusion can be obtained.

Abstract: A single-element magnetoresistive (MR) read head with reduced susceptibility to noise is disclosed. In particular, the present invention addresses the problem of noise generated thermally through contact with the recording medium. The present invention solves this problem by keeping the temperature of the read head at a level that minimizes the noise level. According to a preferred embodiment of the present invention, the shielding material used in the read head is recessed with respect to the magnetic-medium-bearing surface. In an alternative embodiment of the present invention, a thin coating of metal on the read head surface is applied. In yet another embodiment, the read element is operated with a low bias current so as to minimize the thermal effect of power consumption due to electrical resistance. In still another embodiment, the read element makes use of insulating material that is both an electrical insulator and a high quality thermal insulator.

Abstract: A first magnetic shielding film is disposed on one surface of a magnetoresistive effective film in a thickness direction thereof, and a second magnetic shielding film is disposed on the other surface of the magnetoresistive effective film in said thickness direction thereof. The antiferromagnetic films are disposed in between the first magnetic shielding film and the second magnetic shielding film, adjacent to and bonded through exchange interaction with at least one of the first magnetic shielding film and the second magnetic shielding film.

Abstract: A read/write head for a disk drive having a shorting conductor from a shield of the read element to a conductor that runs from the write element to an external electrical contact pad. This allows for the measurement of the electrical isolation between the read sensor and the read shield via the external contact pads. Such a capability allows the electrical isolation to be measured both during the lapping process and subsequent to the heads being diced into separate sliders. This shorting conductor may be in the form of an internal shorting stud or in the form of an interim conductor that passes through the parting zone between adjacent heads. In the latter case, the shorting conductor is broken when the heads are diced so that a head of this embodiment can only be measured for electrical isolation prior to dicing.

Abstract: A high output, magnetoresistive head with a CPP structure is disclosed which reduces or prevents deformation near the air bearing surface of the read element portion layer at the time of air bearing surface processing. In the CPP structure magnetoresistive head, the deformation near the air bearing surface as a result of mechanical polishing during the air bearing surface processing can be reduced by forming deformation prevention layers having a higher shear modulus than a first ferromagnetic layer, and a second ferromagnetic layer between a magnetoresistive film and at least one of a lower shield layer and an upper shield layer.

Abstract: A perpendicular recording write head has ferromagnetic first and second pole pieces which are connected at a back gap and an insulation stack with a write coil layer embedded therein is located between the first and second pole pieces and between a head surface of the write head and the back gap. The second pole piece has a pole tip which is located at the head surface and a recessed ferromagnetic write shield layer. A nonmagnetic isolation layer is located between the second pole piece and the write shield layer and at least one ferromagnetic stud is magnetically connected between the first pole piece layer and the write shield layer and is located between the head surface and the insulation stack.

Abstract: The invention offers a magnetic recording head that includes a substrate, a read sensor, and at least one shield positioned adjacent to the read sensor, wherein the shield contributes to thermal pole-tip recession in an amount less than about 0.5 ?/° C. The invention also offers a magnetic recording head that includes a substrate having a coefficient of thermal expansion, a read sensor, and at least one shield, positioned adjacent to the read sensor, that has a coefficient of thermal expansion within ±2×10?6/° C. of the coefficient of thermal expansion of the substrate. The invention further offers a magnetic recording head that includes a substrate, a read sensor, and at least one shield, positioned adjacent the read sensor, with a thickness of from about 0.05 ?m to about 0.5 ?m.

Abstract: A thin-film magnetic head comprises an inductive type electromagnetic transducer having a first magnetic pole, a second magnetic pole, and a thin-film coil. A recording shield layer made of a magnetic material is formed on the side of the second magnetic pole opposite from the first magnetic pole. A recording shield gap layer made of a nonmagnetic material is formed between the second magnetic pole and the recording shield layer. By way of the recording shield gap layer, the recording shield layer covers at least both lateral parts of the second magnetic pole on the side of the second magnetic pole facing a recording medium.

Abstract: A thin film magnetic head having one or more magneto-resistive (MR) elements. A thermally conductive stud is incorporated in an underlayer of the head, below the bottom shield of the MR element. This stud acts as a heat sink, and enhances the heat flow from the bottom shield to the substrate to thereby reduce thermal contact noise in the device, as well as allowing use of higher bias currents when reading signals from the media.

Abstract: A method for reducing flux concentrating capacity of a shield in a magnetic read/write head positioned to read perpendicular residual magnetic fields on a magnetic media. Permeability of the shield is reduced in a direction oriented perpendicular to the magnetic media by inducing a transverse magnetic bias field within the shield.

Abstract: A magnetoresistive sensor has a high resistance soft magnetic layer disposed between the sensor stack and at least one magnetic shield. The presence of the high resistance soft magnetic layer allows a smaller magnetic read gap to be achieved which results in higher recording density. The susceptibility of the magnetoresistive sensor to defects and electrostatic damage is improved. A disk drive is provided having the novel magnetoresistive sensor.

Abstract: A magnetic sensing element of a current-perpendicular-to-plane (CPP) type that minimizes an increase in effective read track width and prevents side reading is provided. The magnetic sensing element includes a composite film, an upper shield layer, a lower shield layer, and side shield layers. The side shield layers are disposed at the two sides of the composite film in the track width direction between the lower shield layer and the upper shield layer.

Abstract: The object of the present invention is to provide a magnetoresistive magnetic head having good, stable playback characteristics. In an MR head wherein an MR element is interposed between a lower shield layer and an upper shield layer, separated by non-magnetic layers. The lower shield layer and the upper shield layer are formed from a material having high permeability and high resistivity. Since the magnetic shield layers are formed from materials having high permeability and high resistivity, even if friction causes dragging of the head surface, there is effectively no short circuit between the magnetic shield layer and the magnetic element.

Abstract: A magnetic recording head includes an upper shield layer, a lower shield layer, a magnetoresistive film interposed between the upper shield layer and the lower shield layer, and a pair of leads electrically coupled to the magnetoresistive film, in which a pair of side shield layers constituted by portions of the upper shield layer is formed on both sides of the magnetoresistive film, and a spacing between each side shield layer and the magnetoresistive film is formed to be narrower than twice of a spacing between the upper shield layer and the lower shield layer, thereby a side reading amount can be made smaller than a conventional side reading value determined from the spacing between the upper and lower shield layers and a magnetic spacing between the head and a medium.

Abstract: A magnetic reading head is provided. The magnetic reading head reads information recorded on a recording medium having a soft underlayer and a magnetic layer stacked on the soft underlayer, and includes a magneto-resistive element and a pair of shield layers. The magneto-resistive element is positioned over the magnetic layer, keeping a predetermined distance G from the soft underlayer. The pair of shield layers are arranged parallel to the magneto-resistive element, keeping predetermined distances from both sides of the magneto-resistive element. Here, the shield layers have widths less than double of the predetermined distance G. In this structure, by properly adjusting the widths of the shield layers, magnetic fields formed by the magnetization of the recording medium under the shield layers do not affect the magnetoresistive element. As a result, sensitivity of the magnetic reading head can be improved.

Abstract: Provided are a thin film magnetic head and a method of manufacturing the same, which can prevent an output decrease without impairment of productivity and other characteristics, while adapting to an increase in a recording density. In the thin film magnetic head, an MR film is sandwiched in between first and second gap films having electrical insulating properties, which are sandwiched in between first and second shield layers. The first shield layer has an inner layer and an outer layer laminated in order from the MR film, and the second shield layer has an inner layer and an outer layer laminated in order from the MR film. The respective inner layers of the first and second shield layers have hardness higher than that of the respective outer layers thereof so as to prevent the first and second shield layers from deforming.

Abstract: The present invention provides a method of manufacturing a magnetoresistive read head which reduces electrostatic discharge and allows measurement of gap resistances in the head.

Abstract: Side shield structures magnetically shielding a read sensor to block side reading of tracks on a magnetic media. The read heads include bottom and top magnetic shield layers, a read sensor or magnetically sensitive element between the bottom and top magnetic shield layers, and a side shield assembly formed of magnetically shielding material positioned between the bottom and top magnetic shield layers and adjacent at least a portion of the read sensor. In current-in-plane embodiments, the side shield assembly includes a pair of side shields of magnetically shielding material adjacent a lower portion of the read sensor formed on a lower read gap. In current-perpendicular-to-plane embodiments, the side shield assembly includes a pair of side shields extending from the bottom magnetic shield adjacent lower sides of the read sensor and/or a pair of side shields extending from the top magnetic shield adjacent upper sides of the read sensor.

Abstract: An area in which an insulating film is formed over a substrate of a recording/reproducing separated type head is limited to the vicinity of a GMR film. This enables heat of Joule heating by a coil to be guided to the substrate without being obstructed by the insulating film. Electrodes, an upper shield film, a lower shield and a lower pole that are formed in-between are metallic thin films of high thermal conductivity, and accordingly have little influence. Similarly, gap films and a separation film that are positioned in-between, though they are electrically insulating films made of A12O3, have no great influence because of their thinness. According to the invention, a rise of the head's own temperature is restrained by efficiently radiating heat generated by the head itself to the substrate. As a result, it is thereby made possible to provide a highly reliable recording/reproducing separated type head whose deformation quantity is smaller and which can avoid coming into contact with a recording medium.

Abstract: An extraordinary magnetoresistance (EMR) magnetic head is provided including a first shield and a second shield defining a gap adapted for being positioned over a magnetic recording disk. An EMR sensor is positioned between the first shield and the second shield. In order to ensure proper operation of the EMR sensor, a plane in which the EMR sensor is positioned is perpendicular to magnetic flux associated with the magnetic recording disk.

Abstract: A magnetic head having a magnetic shield and/or pole layer that is fabricated as a plurality of laminated layers, in which each layer includes a sublayer thickness of Fe(N) and a sublayer thickness of NiFe(N), and where the relative thickness of these two sublayers is graduated. Particularly, the initially deposited laminations include sublayers of NiFe(N) having a thickness that is substantially greater than the thickness of the Fe(N) sublayers, whereas the finally deposited laminations include sublayers having an Fe(N) thickness that is substantially greater than the thickness of the NiFe(N) sublayers.

Abstract: A magnetoresistive effect sensor uses a shielded-type magnetoresistive effect element using a magnetoresistive effect film formed by a basic configuration of a combination of a free layer, a barrier layer formed on the free layer, and a fixed layer formed on the barrier layer, wherein a sensing current flows substantially perpendicular to the magnetoresistive effect film, and wherein an amorphous material or a microcrystalline material is used in a lower shield.

Abstract: In a thin film magnetic head device including a reading giant magneto-resistive thin film magnetic head element whose electric equivalent circuit is expressed by a series circuit of an equivalent voltage source and a series resistor RH and a parallel capacitor C connected in parallel with said series circuit, inductor L is connected in series with said series resistor RH and a parallel resistor R is connected in series with said parallel capacitor C. The coil L and parallel capacitor C are set such that an angular frequency ?0=1/(LC)1/2, an angular frequency ?1=1/CR and an angular frequency ?H=1/CRH satisfy conditions of ?0>?1 and ?0>?H, preferably ?0>>?1 and ?0>>?H to extend a frequency characteristic toward a high frequency range.

Abstract: A spin valve head configured to operate in a Current-In-Plane (CIP) mode is provided. The spin valve head has an air bearing surface (ABS) and a top and a bottom shield separated by a central region proximate the ABS. A sensor, positioned in the central region, has a proximal end and a distal end, with the proximal end forming a portion of the ABS. A permanent magnet is positioned in the central region and proximate the distal end of the sensor. The permanent magnet being separated from the sensor by a gap layer. The top shield, the bottom shield and the permanent magnet are electrically coupled together to allow for electrical testing of the spin valve head.

Abstract: A magnetoresistive transducer includes a magnetoresistive (MR) film interposed between domain control layers along the surface of a lower non-magnetic gap layer. Lead layers are formed on the domain control layers. An upper non-magnetic gap layer and an upper shield layer are sequentially formed to extend over the MR film and the lead layers. The upper shield layer is opposed to the surfaces of the MR element and the lead layers at a flat boundary or interface. The residual magnetization is supposed to exist in the upper shield layer in the direction of the magnetization established in the domain control layers after the upper shield layer has been subjected to the applied magnetic field for the magnetization of the domain control layers. The residual magnetization can be kept continuous along the flat interface of the upper shield layer. Any magnetic poles are hardly generated along the interface of the upper shield layer.

Abstract: A magnetic transducer including an electrically conductive shield (ECS) which is disposed between the substrate and first magnetic shield is described. The ECS is preferably embedded in an insulating undercoat layer. The ECS is preferably electrically isolated from the magnetic sensor element and is externally connected to a ground available in the disk drive through the arm electronics. Two alternative ways for connecting the ECS to a ground are described. In one embodiment which is only effective with single-ended input type arm electronics, the ECS is connected to a ground through a via to a lead pad for the read head which is connected to the ground of the arm electronics. In a second and more preferred embodiment a separate lead pad is included on the head to allow the ECS to be connected to electronic or case ground when the head is installed in the arm. The extent of the ECS should be sufficiently large to cover the read head portion of the transducer, i.e.

Abstract: A specified amount of N2O or N2 is employed in a process gas of a DC magnetron for sputter depositing single or laminated films of NiFeCo—O—N or NiFeCo—N with a high uniaxial anisotropy HK after annealing these films along their hard axes. The films can be used for shield layers and/or pole piece layers in a magnetic head.

Abstract: A read/write head for a disk drive having a magnetoresistive (MR) read element and an inductive write element suitable for perpendicular recording of data onto a disk having a media layer in which the data is stored perpendicularly to the planar surface of the disk and a soft underlayer (SUL) underneath the media layer to provide a low reluctance return path for the magnetic recording field. The read element includes an MR sensor sandwiched between a pair of shields. The write element includes a vertically-oriented write pole and a horizontally-oriented yoke that connects the write pole and the adjacent shield of the read element. One or more pancake coils are looped around the yoke to produce a magnetic field that is focused by the tip of the write pole which is relatively smaller than the remainder of the write pole. A floating write shield is located downstream of the write pole, the shield having a throat region in close proximity to the write pole and a ramp portion sloping away from the write pole.

Abstract: A separate read/write magnetic head of the present invention includes a magnetoresistive head 11 having a magnetoresistive film 25 disposed between a lower shield 23 and an upper shield 28, both of which are formed on a substrate 21, and a pair of electrodes 26 electrically connected to the magnetoresistive film 25; and an inductive magnetic thin film head 12 having a coil 33 between a lower pole piece 31 and an upper pole piece 35, both of which are disposed on the upper shield 28 of the magnetoresistive head 11 with a separation film 29 being sandwiched therebetween, and through a magnetic gap film 32 and an interlayer insulating film 34. Reduced protrusion of the read head element toward the air bearing surface due to heat deformation caused by changes in ambient temperature can be achieved by configuring the lower shield 23 and the upper shield 28 so that the sum of their thicknesses is 0.4 &mgr;m or more and less than 3.4 &mgr;m.

Abstract: A magnetic material having a low coefficient of thermal expansion of 11.5×10−6/K or less is used for forming at least one of a lower shield or an upper shield. A laminated film comprising a layer of the magnetic material having a low coefficient of thermal expansion of 11.5×10−6/K or less, and an 80 wt % NiFe alloy layer, is used for forming at least one of the lower shield and the upper shield. Thus, the thin film magnetic head having reduced after-record noise and reduced thermal protrusion can be obtained.

Abstract: A ferromagnetic shield material having a minimized anisotropic magneto-resistance effect permits the use of a combined shield/electrical lead for magneto-resistive read elements. The shields/electrical leads may therefore be placed closer together, maximizing the recording density that may be read by a magnetic recording head using a read element having such shields/leads.

Abstract: In a spin value type transducer including two magnetic shield layers, a patterned magnetoresistance element is in direct contact with one of the magnetic shield layers. A permanent magnet layer and an electrode layer are formed on the sides of the patterned magnetoresistance element.

Abstract: In at least one embodiment, the apparatus of the invention is a read sensor which includes a shield, a sensor element, a read gap positioned between the shield and the sensor element, and an extra gap positioned between the shield and the sensor element and adjacent the read gap. The sensor element is positioned in a sensor layer. With the sensor element and the shield separated by only the relatively thin gap layer, high sensitivity of the sensor element is obtained. Further, by placing the relatively thick extra gap between the shield and the sensor layer and about the sensor element, the potential for shorting is minimized. The shield can be planarized to keep the read gap and the sensor layer at, and about, the sensor element substantially planar. This, in turn, results in improved control of sensor track widths and greatly reduces the potential for pooling of photoresist.

Abstract: A read head shield having improved stability includes a ferromagnetic (FM) layer and an anti-ferromagnetic (AFM) layer adjacent the FM layer. The FM layer has a patterned shape and a domain configuration that is defined by a plurality of local magnetic domains that are stabilized in accordance with the patterned shape. The AFM layer is annealed to imprint thereon the stabilized local magnetic domains of the FM layer. The AFM layer operates to increase the stability of the domain configuration of the FM layer thereby providing improved resistance to domain configuration shift caused by the application of a strong magnetic field.

Abstract: A magnetoresistive sensor has a high resistance soft magnetic layer disposed between the sensor stack and at least one magnetic shield. The presence of the high resistance soft magnetic layer allows a smaller magnetic read gap to be achieved which results in higher recording density. The susceptibility of the magnetoresistive sensor to defects and electrostatic damage is improved. A disk drive is provided having the novel magnetoresistive sensor.

Abstract: A read head is provided having having ultrathin read gap layers with improved insulative properties between a magnetoresistive sensor and ferromagnetic shield layers. The read head comprises a magnetoresistive sensor with first and second shield cap layers made of high resistivity permeable magnetic material formed between the first and second ferromagnetic shields and the first and second insulative read gap layers, respectively. The shield cap layers made of Fe—Hf—Ox material, or alternatively, the Mn—Zn ferrite material provide highly resistive or insulating soft ferromagnetic layers which add to the electrically insulative read gap layers to provide increased electrical insulation of the spin valve sensor from the metallic ferromagnetic shields while not adding to the magnetic read gap of the read head.

Abstract: A specified amount of N2O or N2 is employed in a process gas of a DC magnetron for sputter depositing single or laminated films of NiFeCo—O—N or NiFeCo—N with a high uniaxial anisotropy HK after annealing these films along their hard axes. The films can be used for shield layers and/or pole piece layers in a magnetic head.

Abstract: A magnetic material includes a main component expressed by a general formula CoNiFeX, wherein X is at least one element selected from the group consisting of Cr, Ti, V, Ru, Rh, Pd, Os, Ir and Pt, and wherein weight percentages a, b, c and d of Co, Ni, Fe and X contents, respectively, in the main component are such that 40%≦a≦10%, 5%≦b≦20%, 10%≦c≦30%, and 0%<d≦10%.

Abstract: Side shield structures magnetically shielding a read sensor to block side reading of tracks on a magnetic media. The read heads include bottom and top magnetic shield layers, a read sensor or magnetically sensitive element between the bottom and top magnetic shield layers, and a side shield assembly formed of magnetically shielding material positioned between the bottom and top magnetic shield layers and adjacent at least a portion of the read sensor. In current-in-plane embodiments, the side shield assembly includes a pair of side shields of magnetically shielding material adjacent a lower portion of the read sensor formed on a lower read gap. In current-perpendicular-to-plane embodiments, the side shield assembly includes a pair of side shields extending from the bottom magnetic shield adjacent lower sides of the read sensor and/or a pair of side shields extending from the top magnetic shield adjacent upper sides of the read sensor.

Abstract: A magnetic head for reading information from a magnetic medium is provided. The magnetic head includes a substrate, having a substrate thermal coefficient of expansion, and a read element positioned above the substrate. The head also includes a shield, positioned above the substrate and adjacent the read element, which has a shield thermal coefficient of expansion that substantially matches the substrate thermal coefficient of expansion. The shield absorbs stray magnetic fields from the magnetic medium, which emanate from stored data that is adjacent to a data element that is directly beneath and read by the magnetoresistive read element. This shield may also serve to provide electrical contact for the read element. The magnetic thermal coefficient of expansion and electrical properties of the shield may be suitably optimized through appropriate choice of component materials and structure.

Abstract: A magneto-optical read head for detecting magnetic transitions representing data stored in a magnetic recording medium as a sense layer having an optical property that is magnetic field-dependent, two magnetic shield layers respectively disposed on opposite sides of the sense layer and allowing magnetic flux from substantially only one of the magnetic transitions to interact with the sense layer at a time, with one of the magnetic shield layers being transparent at a wavelength allowing light at that wavelength to enter into and exit from the sense layer.