A heat-assisted magnetic recording (HAMR) head has a protective multilayer confined to a window of the disk-facing surface of the slider that surrounds the near-field transducer (NFT) end and write pole end. The protective multilayer is made up of a first film of silicon nitride directly on and in contact with the NFT end and the write pole end and a second film of a metal oxide on and in contact with the silicon nitride film. The silicon nitride film is preferably formed by RIBD but is thin enough so that it does not contain any significant amount of other compounds. The metal oxide is preferably silicon dioxide, or alternatively an oxide of hafnium, tantalum, yttrium or zirconium, and together with the silicon nitride film provides a protective multilayer of sufficient thickness to be optically transparent to radiation and resistant to thermal oxidation.

Systems and methods are disclosed for magnetoresistive asymmetry (MRA) compensation using a digital compensation scheme. In certain embodiments, a method may comprise receiving an analog signal at a continuous-time front end (CTFE) circuit, and performing analog offset compensation to constrain an extremum of the analog signal to adjust a dynamic range based on an input range of an analog-to-digital converter (ADC), rather than to modify the analog signal to have a zero mean. The method may further comprise converting the analog signal to a digital sample sequence via the ADC; performing, via a digital MRA compensation circuit, digital MRA compensation on the digital sample sequence; receiving, via a digital backend (DBE) subsystem, the digital sample sequence prior to digital MRA compensation; and generating, via a DBE, a bit sequence corresponding to the analog signal based on an output of the DBE subsystem and an output of the digital MRA compensation circuit.

A Data Storage Device (DSD) includes one or more magnetic disks with each magnetic disk including at least one recording surface. A segment mapping is generated having a predetermined number of segment entries per recording surface with each segment entry corresponding to a data segment of the recording surface. One or more segment entries include a first logical address corresponding to a first logical data block that begins in the corresponding data segment and at least one of the data segments is configured to store multiple logical data blocks. A target segment entry is located in the segment mapping corresponding to a highest logical address less than or equal to a requested logical address of a read command and a head of the DSD is moved to a beginning portion of a target data segment corresponding to the target segment entry to perform the read command.

A hard disk drive (HDD) includes a heat-assisted magnetic recording (HAMR) head. The HAMR head includes one or more features comprising a nanoparticle-reinforced plasmonic matrix. The nanoparticle-reinforced plasmonic matrix comprises a plasmonic metal and a plurality of nanoparticles dispersed in the plasmonic metal. The nanoparticles comprise a transparent conductive oxide.

A heat-assisted magnetic recording head includes a slider body, a laser, a submount, and a laser heater. The slider body is configured to contain components of the heat-assisted magnetic recording head. The laser is configured to emit electromagnetic radiation. The submount is configured to couple the laser to the slider body. The laser heater is configured to apply heat to the laser. The laser heater disposed on a surface of the slider body.

A heat-assisted magnetic recording head comprises a near-field transducer (NFT). The NFT comprises a thermally-stabilized plasmonic alloy, wherein the thermally-stabilized plasmonic alloy comprises a plasmonic metal and at least one alloying metal.

An external cavity laser of a recording head includes a channel waveguide that delivers light towards a media-facing surface of the recording head. The laser includes an externally mounted part with an active region having a longitudinal axis corresponding to a light propagation direction of the channel waveguide. The externally mounted part has a reflective back facet and anti-reflective front facet. The laser includes a near-field transducer at an end of the channel waveguide proximate the media facing surface. The reflective back facet and the near-field transducer define a resonator of the external cavity laser.

A magnetic recording medium includes a substrate, and a magnetic recording layer including magnetic grains having an L1.sub.0 structure. The magnetic recording layer is (001) oriented, and a surface of growth of the magnetic recording layer includes a (001) plane, a (111) plane, and planes equivalent to the (111) plane. An area ratio of the (111) plane and the planes equivalent to the (111) plane, represented by (A.sub.111+A.sub.111e)/(A.sub.001+A.sub.111+A.sub.111e), is in a range of 0.2 to 0.7, where A.sub.111 denotes an area of the (111) plane, A.sub.111e denotes an area of the planes equivalent to the (111) plane, and A.sub.001 denotes an area of the (001) plane.

According to one embodiment, when an inspection of a defect of a recording surface of the magnetic disk is carried out by using the first processing section and the second processing section on the basis of the output of the gap sensor, a magnetic disk device is configured to compare a threshold defined on the basis of outputs of the first processing section at a plurality of tracks excluding a track which is an inspection object and an output of the first processing section at the track which is the inspection object with each other and, when the output of the first processing section at the track which is the inspection object exceeds the threshold, detect that there is a defect on the track concerned of the magnetic disk.

According to one embodiment, a magnetic recording and reproducing device includes a perpendicular magnetic recording medium, a perpendicular magnetic recording head, a thermal assisted magnetic recording medium, and a thermal assisted magnetic recording head.