A method includes generating, during manufacture of a heat-assisted magnetic recording (HAMR) disk drive, a temperature compensation equation for a compensation factor using initial operating currents supplied to a laser diode of the disk drive at different initial operating temperatures and an efficiency value based on the initial operating temperatures. The operating currents are representative of currents for recording data to or erasing data from a magnetic recording medium. The temperature compensation equation is stored in the disk drive. A subsequent efficiency value is determined based on at least one of the initial operating temperatures and an operating temperature differing from the initial operating temperatures. An updated compensation factor at the operating temperature is determined during field operation using the temperature compensation equation and the subsequent efficiency value. An updated operating current is calculated using the updated compensation factor and the operating temperature. A current supplied to the laser diode for a subsequent write operation is adjusted to the updated operating current.

According to one embodiment, a magnetic recording apparatus measures and stores recording signal quality of a disk at an initial stage, inspects the recording signal quality before data is recorded, determines whether or not the recording signal quality obtained in the inspection satisfies a standard when compared to the stored recording signal quality at the initial stage, adjusts, based on a result of the determination, light irradiation power of a light irradiation element so as to satisfy the standard, determines a read offset amount based on a result of the adjustment, and performs control so that a position of a read head is shifted based on the determined read offset amount.

The present invention relates to the technical field of superlattice magneto-optical material technologies, and in particular, to a superlattice material, and a preparation method and application thereof. According to description of embodiments, the superlattice material provided in the present invention has both a relatively good magnetic property of a ferrous garnet material and a good photoelectric absorption characteristic of a two-dimensional semiconductor material such as graphene. Magneto-optical Kerr effect data obtained through testing shows that: A saturated magneto-optical Kerr angle of the superlattice material in the present invention is 13 mdeg in a magnetic field of 2500 Oe, and a magneto-optical Kerr angle of the superlattice material is increased by 2.5 times compared with a nonsuperlattice ferrimagnetic thin film material into which no two-dimensional material is inserted, thereby achieving magneto-optical effect enhancement.

The present invention relates to the technical field of superlattice magneto-optical material technologies, and in particular, to a superlattice material, and a preparation method and application thereof. According to description of embodiments, the superlattice material provided in the present invention has both a relatively good magnetic property of a ferrous garnet material and a good photoelectric absorption characteristic of a two-dimensional semiconductor material such as graphene. Magneto-optical Kerr effect data obtained through testing shows that: A saturated magneto-optical Kerr angle of the superlattice material in the present invention is 13 mdeg in a magnetic field of 2500 Oe, and a magneto-optical Kerr angle of the superlattice material is increased by 2.5 times compared with a nonsuperlattice ferrimagnetic thin film material into which no two-dimensional material is inserted, thereby achieving magneto-optical effect enhancement.

An apparatus includes a first waveguide core extending along a light-propagation direction and configured to receive light from a light source at a combined transverse electric (TE) mode and a transverse magnetic (TM) mode. A second waveguide core is spaced apart from the first waveguide core and is configured to couple light at a TM mode to the second waveguide core. A near-field transducer (NFT) is disposed at a media-facing surface of a write head, the NFT receiving the light from the first waveguide core or the second waveguide core and heating a magnetic recording medium in response thereto.

A data storage device is disclosed comprising a disk surface comprising a magnetic recording layer comprising a first magnetic material having a first coercivity intermixed with a second magnet material having a second coercivity higher than the first coercivity, and a head comprising a write coil configured to magnetize the magnetic recording layer in order to write data to the disk surface. The data is written to the disk surface by configuring the magnetic recording layer into one of at least three recording states, and the data is read from the disk surface by reading the magnetic recording layer using the head to generate a multi-level read signal, where each level of the read signal corresponds to one of the recording states.

A system determines the data stored on a piece of magnetic media by obtaining an image that represents the magnetic state of the piece of magnetic media using a magneto-optic image sensor. In an example, the image sensor is connected to a mechanism that moves over the piece of magnetic media, and the system takes a plurality of images which are stitched together into a composite image of the state of the piece of magnetic media. The system analyzes the image to identify regions that contain data, extracts the encoded data from the regions. The encoded data is decoded in accordance with an encoding scheme used by the piece of magnetic media. In some examples, a file structure is applied to the data and data files are recovered from the image. In various examples, the piece of magnetic media can be hard disk media, floppy disk media, or magnetic tape.

A recording head includes a channel waveguide that delivers light to a media-facing surface. A near-field transducer (NFT) is at an end of the channel waveguide and proximate to the media-facing surface. A laser including an active region has a longitudinal axis corresponding to a propagation direction of the channel waveguide. The active region includes a back facet and a front facet proximate the NFT. The front facet has a surface shape configured to suppress back reflection of the light.

A laser beam is directed through a transmissive axicon telescope or a reflective axicon telescope such as in a magneto-optic Kerr effect metrology system. With the transmissive axicon telescope, a Gaussian beam profile is directed through a first axicon lens and a second axicon lens. The first axicon lens and second axicon lens transfer the Gaussian beam profile of the laser beam to a hollowed laser ring. The laser beam with a hollowed laser ring can be directed through a Schwarzschild reflective objective. With the reflective axicon telescope, the laser beam is directed through two conical mirrors that are fully reflective. One of the conical mirrors defines a central hole that the laser beam passes through.

A recording head includes a substrate, a read transducer, a waveguide core, and a near-field transducer at an end of the waveguide core proximate a media-facing surface. The recording head includes a magnetic write pole and coil. A laser diode unit with one or more non-self-supporting layers of crystalline material region is transfer printed between layers of the recording head.