According to one embodiment, a magnetic disk device includes a rotatable disk-shaped recording medium, a magnetic head including a write head having a main magnetic pole that applies a recording magnetic field to the recording medium, an assist element that assists magnetic recording by the main magnetic pole, and a plurality of thermal actuators that control a head gradient with respect to the recording medium, and a controller which includes a detection unit configured to detect deterioration of the magnetic head, and changes a head gradient of the magnetic head by the thermal actuator according to the detected deterioration.

According to one embodiment, a magnetic disk device includes a rotatable disk-shaped recording medium, a magnetic head including a write head having a main magnetic pole that applies a recording magnetic field to the recording medium, an assist element that assists magnetic recording by the main magnetic pole, and a plurality of thermal actuators that control a head gradient with respect to the recording medium, and a controller which includes a detection unit configured to detect deterioration of the magnetic head, and changes a head gradient of the magnetic head by the thermal actuator according to the detected deterioration.

According to one embodiment, an evaluation method of a magnetic head is disclosed. The method can include acquiring an electrical signal obtained from a magnetic element when supplying a first alternating current to a coil of a magnetic head and supplying a second current to the magnetic element. The magnetic head includes a first magnetic pole, a second magnetic pole, and a coil. The magnetic element is provided between the first magnetic pole and the second magnetic pole, and includes a first magnetic layer. The method can include detecting a time required for a change of an electrical resistance of the magnetic element based on a time when a polarity of the first alternating current is reversed based on the electrical signal.

According to one embodiment, an evaluation method of a magnetic head is disclosed. The method can include acquiring an electrical signal obtained from a magnetic element when supplying a first alternating current to a coil of a magnetic head and supplying a second current to the magnetic element. The magnetic head includes a first magnetic pole, a second magnetic pole, and a coil. The magnetic element is provided between the first magnetic pole and the second magnetic pole, and includes a first magnetic layer. The method can include detecting a time required for a change of an electrical resistance of the magnetic element based on a time when a polarity of the first alternating current is reversed based on the electrical signal.

A PMR (perpendicular magnetic recording) write head is configured for measurements at the slider level and wafer-level processing stages that will allow a determination of the pole width at a position A (PWA) using the results of a resistance measurement between a main pole (MP) and surrounding write shields (WS) with a layer of conductor in the write gap and a layer of insulating material replacing the side gaps. Knowledge of an accurate value of PWA allows adjustments to be made in the processing of sliders on each rowbar which, in turn improves the capability of delivering the desired statistical variation (sigma) in the distribution of erasure widths for AC signals (EWACS) in a given design which, in turn, gives better overall performance in hard disk drive (HDD) applications.

A PMR (perpendicular magnetic recording) write head is configured for measurements at the slider level and wafer-level processing stages that will allow a determination of the pole width at a position A (PWA) using the results of a resistance measurement between a main pole (MP) and surrounding write shields (WS) with a layer of conductor in the write gap and a layer of insulating material replacing the side gaps. Knowledge of an accurate value of PWA allows adjustments to be made in the processing of sliders on each rowbar which, in turn improves the capability of delivering the desired statistical variation (sigma) in the distribution of erasure widths for AC signals (EWACS) in a given design which, in turn, gives better overall performance in hard disk drive (HDD) applications.

A magnetic apparatus has a media-facing surface (MFS), a pole, a top shield, a back gap and coil(s). The pole includes a yoke extension, a yoke between the yoke extension and the MFS, and a pole tip between the yoke and the MFS. The write gap is between the top shield and the pole tip. The back gap is recessed from the ABS and magnetically and physically connects the top shield to the yoke. The coil(s) energize the pole and have multiple turns. Part of a first turn is between the yoke and the top shield. Part of a second turn is recessed from the MFS and aligned with part of the yoke extension. Part of the first turn is between the part of the second turn and the MFS. The back gap is between part of the first turn and part of the second turn.

A magnetic apparatus has a media-facing surface (MFS), a pole, a top shield, a back gap and coil(s). The pole includes a yoke extension, a yoke between the yoke extension and the MFS, and a pole tip between the yoke and the MFS. The write gap is between the top shield and the pole tip. The back gap is recessed from the ABS and magnetically and physically connects the top shield to the yoke. The coil(s) energize the pole and have multiple turns. Part of a first turn is between the yoke and the top shield. Part of a second turn is recessed from the MFS and aligned with part of the yoke extension. Part of the first turn is between the part of the second turn and the MFS. The back gap is between part of the first turn and part of the second turn.

A manufacturing method for a magnetic head forms a leading shield having a top surface. The top surface of the leading shield includes first and second portions. The second portion is located farther from a medium facing surface than is the first portion, and recessed from the first portion. A first gap layer is then formed on the first portion. Then, a magnetic layer including an initial first side shield, an initial second side shield and a coupling section connecting them is formed using a mold. The mold is then removed. The coupling section is then removed by etching the magnetic layer. A second gap layer and a main pole are then formed in this order.

Apparatuses and methods for providing thin shields in a multiple sensor array are provided. One such apparatus is a magnetic read transducer including a first read sensor, a second read sensor, and a shield assembly positioned between the first read sensor and the second read sensor at an air bearing surface (ABS) of the magnetic read transducer, the shield assembly including a first shield layer assembly having a first footprint with a first area, and a second shield layer assembly having a second footprint with a second area, where the second area is greater than the first area.