Head gimbal assembly and magnetic disk device having the same

A magnetic disk device comprising:

• a disk-shaped recording medium which is rotatably provided;
• and
• a head gimbal assembly which comprises a suspension, a gimbal portion provided in the suspension, and a magnetic head supported by the gimbal portion,
• wherein the magnetic head comprises a slider which includes an air bearing surface including a pair of side edges, a pair of side surfaces along the pair of side edges of the air bearing surface, a leading-side end surface, and a trailing-side end surface, and a head portion which is provided in the slider and records and reads data, and
• wherein the slider comprises a leading-side step portion provided on a leading-side end portion of the air bearing surface, a trailing-side step portion which is provided on a trailing-side end portion of the air bearing surface and in which the head portion is imbedded, a deep groove which is formed between the leading-side step portion and the trailing-side step portion and is open to the air bearing surface and the pair of side surfaces, and a pair of partition walls which extends from the trailing-side step portion toward the leading-side step portion along the pair of side surfaces to close a part of a side surface opening of the deep groove,
• the side surface opening of the deep groove has a constant width in a thickness direction of the slider, and
• each of the partition walls is shaped in a rib and includes an outer side surface which is flush with the side surface and an inner side surface which is opposite to the outer side surface and faces the deep groove so as to define a recess which is closed on a downstream side and is open toward the deep groove.