Abstract: On the trailing side of a main pole air bearing surface of a magnetic head for perpendicular recording, the central portion is formed closer to the leading side than the corners on the trailing side, such that the main pole air bearing surface is formed in the shape of a recess with respect to the tailing side. As a result, it is possible to linearize the magnetic field distribution on the trailing side whereby the magnetic reversal is determined, and to record a bit without curving the shape of magnetic reversal.

Abstract: The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Abstract: A hard disk drive is disclosed which is highly reliable against environmental changes. A breather hole is formed in an enclosure which houses therein a magnetic disk and a magnetic head. An opening/closing control mechanism is provided in the breather hole. The opening/closing control mechanism is made up of a valve member for opening and closing the breather hole, a lever which supports the valve member at a fulcrum, a spring which urges the valve member in a closing direction through the lever, and a solenoid which causes the valve member to be displaced in an opening direction against the biasing force of the spring. When the hard disk drive is not operating, the breather hole formed in the enclosure 1 is closed to seal the enclosure hermetically.