Exchange-coupled film, spin valve film, thin film magnetic head, magnetic head apparatus, and magnetic recording/reproducing apparatus
An exchange-coupled film has a ferromagnetic layer sandwich comprising a first ferromagnetic layer containing a ferromagnetic material of the body-centered cubic structure and a pair of second ferromagnetic layers containing a ferromagnetic material of the face-centered cubic structure and formed on respective sides of the first ferromagnetic layer; and an antiferromagnetic layer containing a disordered alloy and formed on one of the second ferromagnetic layers. It yields sufficient exchange coupling energy even in smaller thickness of the antiferromagnetic layer than before, whereby it becomes feasible to decrease the thickness of the exchange-coupled film.
1. An exchange-coupled film in which an antiferromagnetic layer and a ferromagnetic layer sandwich are stacked and in which a direction of magnetization of the ferromagnetic layer sandwich is pinned,
wherein said ferromagnetic layer sandwich comprises a first ferromagnetic layer containing a ferromagnetic material of the body-centered cubic structure, and a pair of second ferromagnetic layers containing a ferromagnetic material of the face-centered cubic structure and formed on respective sides of the first ferromagnetic layer, and
wherein said antiferromagnetic layer contains a disordered alloy chosen from the group consisting of IrMn alloys, RuRhMn alloys, FeMn alloys and RuMn alloys, and said antiferromagnetic layer is kept in contact with one of said second ferromagnetic layers, and
wherein said antiferromagnetic layer has a thickness of 10 nm less and
wherein said exchange-coupled film yields a high exchange coupling energy Jk of not less than 263 μJ/m 2 .
2. The exchange-coupled film according to claim 1 , wherein the ferromagnetic layer sandwich further comprises a third ferromagnetic layer placed through a nonmagnetic intermediate layer on the opposite side to the antiferromagnetic layer with the other second ferromagnetic layer in between.
3. A spin valve film comprising the exchange-coupled film as set forth in claim 1 ; a nonmagnetic, conductive layer laid on the ferromagnetic layer sandwich of the exchange-coupled film; and a free layer laid on the nonmagnetic, conductive layer and containing a ferromagnetic material.
4. A thin film magnetic head comprising the spin valve film as set forth in claim 3 , and a pair of magnetic shield layers placed at positions where the spin valve film is sandwiched therebetween from both sides in a stack direction of the spin valve film, and containing a soft magnetic material.
5. The thin film magnetic head according to claim 4 , comprising a pair of electrode layers electrically connected to the spin valve film and adapted for allowing an electric current to flow parallel to a film surface of the spin valve film.
6. The thin film magnetic head according to claim 4 , comprising a pair of electrode layers electrically connected to the spin valve film and adapted for allowing an electric current to flow perpendicular to a film surface of the spin valve film.
7. A magnetic head apparatus comprising the thin film magnetic head as set forth in claim 4 ; and a head supporting device for supporting the thin film magnetic head.
8. A magnetic recording/reproducing apparatus comprising the magnetic head apparatus as set forth in claim 7 ; and a magnetic recording medium for implementing magnetic recording/reproduction in collaboration with the thin film magnetic head of the magnetic head apparatus.
9. The exchange-coupled film according to claim 1 , wherein said antiferromagnetic layer has a thickness in the range of 5 to 10 nm.