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 an embodiment, a controller of a magnetic disk device executes control such that detection of touchdowns of one or more first magnetic heads and detection of touchdowns of one or more second magnetic heads are executed at different timings. In addition, the controller executes control such that touchdowns of the one or more first magnetic heads are detected at different timings and touchdowns of the one or more second magnetic heads are detected at different timings.

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head including a read head, a write head, a heater and the magnetic head, and a sensor and the control section. The control section when applying electric power to the heater, the control section predicts, on the basis of a relationship between a value of the electric power to be applied to the heater and an output value of a spectrum at a pulse frequency of a DC output of the sensor in a state where pulsed electric power is applied to the heater, the output value of the spectrum, and detects contact between the magnetic head and the magnetic disk before the predicted output value of the spectrum becomes less than or equal to a threshold.

According to an embodiment, a controller of a magnetic disk device executes control such that detection of touchdowns of one or more first magnetic heads and detection of touchdowns of one or more second magnetic heads are executed at different timings. In addition, the controller executes control such that touchdowns of the one or more first magnetic heads are detected at different timings and touchdowns of the one or more second magnetic heads are detected at different timings.

A method includes producing a first surface acoustic wave (SAW) on a magnetic head slider using a first interdigitated transducer (IDT), wherein the SAW has a first set of wave characteristics. The method also includes receiving the first SAW at a second IDT on the magnetic head slider. The method also includes analyzing the SAW for a second set of wave characteristics. The method also includes determining, based on the analyzing, that a substance having at least one characteristic is located in a path of the SAW on the magnetic head slider.

Methods and systems are disclosed for controlling fly-height of a read/write (RW) head. In an embodiment, a RW channel detects a servo gate signal and toggles a mode signal within a preamplifier from a RW data mode signal to a fly-height control (FHC) mode signal. In response to the FHC mode signal, the RW channel transmits FHC data over a differential interface to the preamplifier.

A heat-assisted magnetic recording (HAMR) hard disk drive has a gas-bearing slider supporting a near-field transducer (NFT) and a NFT temperature sensor (NTS). An optional first IVC circuitry may provide a bias voltage to the slider body to assure substantially zero electrical potential between the slider body and the disk to minimize slider-disk contact and lubrication pick-up. A second IVC circuitry operates independently of the first IVC circuitry and provides a negative bias voltage to the NTS (and the connected NFT) relative to the disk to minimize the adverse effects of excessive heating on the NFT.

Various illustrative aspects are directed to a data storage device comprising a slider with a resistive temperature detector with a first resistance, a resistance detection circuit electrically coupled to the first resistance and comprising a low and high frequency path corresponding to a DC and AC mode, respectively, and one or more processing devices configured to: bias the first resistance with a voltage bias, where the first resistance is coupled to a first and second amplifier, control a pulse generator to add a bias pulse on the HF path to generate a HF resistance detection signal, where the second amplifier is biased using the voltage bias and the bias pulse, control a clock to chop a LF signal at the first amplifier on the LF path, demodulate the chopped LF signal to generate a LF resistance detection signal, and concurrently process the HF and LF resistance detection signals.

According to one embodiment, a recording head includes a main pole and a first shield. The first shield includes a distal end portion projecting from an air bearing surface of a slider. The distal end portion includes a distal end surface which includes a first shield edge opposing the main pole with a write gap and a second shield edge spaced apart from the first shield edge in a trailing end side. A distal end portion of the main pole projects from the distal end surface. When a length between the distal end portion of the main pole and the second shield edge is L1, the projection amount of the distal end portion of the main pole is h2, a flying pitch is D1, and a protrusion pitch angle is D2, the recording head satisfies a relationship of: L1h2/(D1+D2).

An apparatus comprising a slider is configured for heat-assisted magnetic recording. The slider comprises a media-facing surface. One or more reader elements are positioned in a reader region of the slider, and the one or more reader elements have an average first elevation at the media-facing surface. One or more writer elements are positioned in a writer region of the slider, and the one or more writer elements have an average second elevation at the media-facing surface. The average second elevation is less than the average first elevation.