A recording medium recording a magnetic material simulation program includes: acquiring a shape model including element regions of a shape of a core, property information indicating physical properties of a magnetic material of the core, and coil current information indicating a time change in a current through a coil around the core; specifying a first current density of the coil at a first time, based on the coil current information; computing, using the property information and the first current density, first index values at the first time for positions in the shape model; computing, using the first index values, a charge density of each element region; specifying a second current density of the coil at a second time, based on the coil current information; and computing, using the property information, the second current density, and the charge density, second index values at the second time for the positions.

Systems and techniques relate to current slew control circuits. According to an aspect, a system implementing the quadratic slew control aspects comprises a disk; a read/write head; and a slew control circuit coupled to the read/write head, the slew control circuit configured to: receive an input current signal, apply a slew current to the input current signal in response to a change in a power setting for the read/write head, and provide an output current signal that is adjusted to a quadratic current slew based on the applied slew current, the output current signal generating an output voltage characterized by a linear slew and controlling a movement of the read/write head over the disk.

Various illustrative aspects are directed to a data storage device comprising a disk and a read/write head configured to read data from and write data to the disk. The read/write head comprises a write pole tip and a transducer configured near the write pole tip. One or more processing devices are mounted on or near the read/write head and generate an AC current that is applied to the transducer to cause the transducer to generate a high frequency auxiliary field that is applied to the disk. The one or more processing devices may be an RF source IC mounted on or near a slider on which the read/write head is integrated or mounted.

A thermally-assisted magnetic recording head includes a main pole and a plasmon generator. The plasmon generator includes a first material portion and a second material portion formed of different materials. The first material portion is located away from the medium facing surface. The second material portion includes a near-field light generating surface. The main pole has a front end face including a first end face portion and a second end face portion. The near-field light generating surface, the first end face portion and the second end face portion are arranged in this order along the direction of travel of a recording medium.

A data storage device can include a recording medium; a controller unit to generate control signals in response to write information and write commands; and a transducer section coupled to receive the controls signals, and in response, write the write information into the recording medium and form a data protection pattern in the recording medium adjacent to the write information.