A bottom shield in a read head is modified by including a non-magnetic decoupling layer and second magnetic layer on a conventional first magnetic layer. The second magnetic layer has a magnetization that is not exchange coupled to the first magnetic layer, and a domain structure that is not directly affected by stray fields due to domain wall motion in the first magnetic layer. Accordingly, the modified bottom shield reduces shield related noise on the reader and will provide improved signal to noise (SNR) ratio and better reader stability. The second magnetic layer may be further stabilized with one or both of an antiferromagnetic coupling scheme, and insertion of an antiferromagnetic pinning layer. In dual readers, the modified bottom shield is used in either the bottom or top reader although in the latter, first magnetic layer thickness is reduced to maintain reader-to-reader spacing and acceptable bit error rate (BER).

An apparatus comprises a slider comprising an air bearing surface (ABS). The slider comprises a reader, a writer, and a reader heater. The reader heater is configured to cause a protrusion of the ABS proximate the reader, and the reader heater comprises a first planar loop and a second planar loop, wherein the first and second loops are in the same plane.

An apparatus for recording information on a magnetic medium can be provided, which can include, for example, a plasmonic transducer(s)/waveguide and a resonant antenna(s) of different forms and shapes spaced at a distance from the plasmonic transducer(s)/waveguide, where the resonant antenna(s) can be configured to receive or maintain the magnetic medium thereon. The resonant antenna(s) can be in the form of nanorods, spheres, or other plasmonic structures able to support a localized surface plasmon. The resonant antenna(s) can be achieving either by structuring the metal below recording media or by drop-casting/depositing nanoparticles below a recording media. The size of the nanoantenna can be based on the achieving high field enhancement between plasmonic transducer/waveguide and matching an impedance of the transducer(s).

An apparatus, according to one embodiment, includes: write transducers, each having: a first write pole having a pole tip, and a second write pole having a pole tip, the pole tips extending from a media facing side of the respective write pole. The pole tip of the second write pole is configured to emanate magnetic flux directly from the media facing side toward a magnetic medium. Each write transducer has a nonmagnetic write gap between the pole tips of the write poles, and a first high moment layer between the write gap and the pole tip of the second write pole. The first high moment layer has a higher magnetic moment than that of the pole tip of the second write pole. Moreover, the first high moment layer protrudes beyond a plane extending along a media facing side of the pole tips of the first and second write poles.

A bottom shield in a read head is modified by including a non-magnetic decoupling layer and second magnetic layer on a conventional first magnetic layer. The second magnetic layer has a magnetization that is not exchange coupled to the first magnetic layer, and a domain structure that is not directly affected by stray fields due to domain wall motion in the first magnetic layer. Accordingly, the modified bottom shield reduces shield related noise on the reader and will provide improved signal to noise (SNR) ratio and better reader stability. The second magnetic layer may be further stabilized with one or both of an antiferromagnetic coupling scheme, and insertion of an antiferromagnetic pinning layer. In dual readers, the modified bottom shield is used in either the bottom or top reader although in the latter, first magnetic layer thickness is reduced to maintain reader-to-reader spacing and acceptable bit error rate (BER).

A read head includes a permanent magnet (PM) layer formed up to 100 nm behind a free layer where PM layer magnetization may be initialized in a direction that adjusts free layer (FL) bias point, and shifts sensor asymmetry (Asym) closer to 0% for individual heads at slider or Head Gimbal Assembly level to provide a significant improvement in device yield. Asym is adjusted using different initialization schemes and initialization directions. With individual heads, initialization direction is selected based on a prior measurement of asymmetry. The PM layer is CoPt or CoCrPt and has coercivity from 500 Oersted to 1000 Oersted. The PM layer may have a width equal to the FL, or in another embodiment, the PM layer adjoins a backside of the top shield and has a width equal to or greater than that of the FL.

A bottom shield in a read head is modified by including a non-magnetic decoupling layer and second magnetic layer on a conventional first magnetic layer. The second magnetic layer has a magnetization that is not exchange coupled to the first magnetic layer, and a domain structure that is not directly affected by stray fields due to domain wall motion in the first magnetic layer. Accordingly, the modified bottom shield reduces shield related noise on the reader and will provide improved signal to noise (SNR) ratio and better reader stability. The second magnetic layer may be further stabilized with one or both of an antiferromagnetic coupling scheme, and insertion of an antiferromagnetic pinning layer. In dual readers, the modified bottom shield is used in either the bottom or top reader although in the latter, first magnetic layer thickness is reduced to maintain reader-to-reader spacing and acceptable bit error rate (BER).

A read head includes a permanent magnet (PM) layer formed up to 100 nm behind a free layer where PM layer magnetization may be initialized in a direction that adjusts free layer (FL) bias point, and shifts sensor asymmetry (Asym) closer to 0% for individual heads at slider or Head Gimbal Assembly level to provide a significant improvement in device yield. Asym is adjusted using different initialization schemes and initialization directions. With individual heads, initialization direction is selected based on a prior measurement of asymmetry. The PM layer is CoPt or CoCrPt and has coercivity from 500 Oersted to 1000 Oersted. The PM layer may have a width equal to the FL, or in another embodiment, the PM layer adjoins a backside of the top shield and has a width equal to or greater than that of the FL.

Disclosed in the embodiments of the present invention are a laser writing apparatus and method for programming magnetoresistive devices. The apparatus comprises: a substrate, a magnetoresistive sensor and a thermal control layer which are sequentially arranged in a stacked manner. A non-magnetic insulating layer for electrical isolation is provided between the magnetoresistive sensor and the thermal control layer. The magnetoresistive sensor is composed of a magnetoresistive sensing unit which is a multilayer thin-film stacked structure containing an anti-ferromagnetic layer. The laser writer programming apparatus is used during the laser writer programming phase, along with varied parameters of the thermal control layers and/or magnetoresistive sensors, to change the thermal gradient produced by the laser on the magnetoresistive sensor, to increase or decrease the temperature change of the magnetoresistive sensor at the same laser power, and the film parameters use d to do this include material composition and film thickness. Through the embodiments of this invention, high precision laser programming of a magneotresistive sensor is obtained, with improved magnetoresistive sensor manufacturability, improved magnetoresistive sensor noise performance, and with improved magnetoresistive sensor detectability.

According to one embodiment, a magnetic disk device conforming to perpendicular magnetic recording includes a magnetic disk, a recording head, and a controller. The head includes a main magnetic pole, a return magnetic pole, a recording coil, and a conductive member in which end surfaces are connected to opposed surfaces of a write gap which is opposed to a distal portion of the main magnetic pole and a distal portion of the return magnetic pole, and a resistance value varies. The controller applies a current to the recording coil to excite the magnetic flux in the recording operation, and applies a current at a constant voltage to the magnetic circuit via the comductive member.