Patent ID: 7349186

Claim:
A magnetic head comprising: a first electrode layer; a free layer composed of a first ferromagnetic layer deposited over the first electrode layer, on a side thereof, adjacent to an air bearing surface, with a first insulating layer interposed therebetween; a pinned layer composed of a second ferromagnetic layer deposited over the first electrode layer, at a location away from the air bearing surface, with a second insulating layer interposed therebetween; an electrode for causing a tunneling current to flow from the first electrode layer to the second ferromagnetic layer via the second insulating layer; and a signal detection circuit for detecting voltage change occurring between the first ferromagnetic layer and the first electrode layer, due to change in the magnetization direction of the first ferromagnetic layer, occurring by a magnetic field impressed on the first ferromagnetic layer by a medium, wherein the signal detection circuit has input impedance against AC input, greater than impedance of a multilayered body of the first insulating layer, and the free layer.