US 7,733,612 B2Granted

GMR device of the CPP structure, thin-film magnetic head, head gimbal assembly, and hard disk system

AssigneeTDK Corporation

InventorsDaisuke Miyauchi, Takahiko Machita

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Abstract

In the GMR device of the CPP structure using the synthetic pinned layer as the fixed magnetization layer (pinned layer), the width W1 of the inner pin layer is set at 50 nm or less; the fixed magnetization layer is configured in such a way as to have a given angle range of tapers at both its ends as viewed from the medium opposite plane; the magnetic volume ratio between the inner and the outer pin layer is allowed to lie in the range of 0.9 to 1.1; and the magnetic thickness ratio between the inner and the outer pin layer is set at 0.8 or less. It is thus possible to make the outer pin layer thin at no cost of the thickness of the inner pin layer forming a part of the synthetic pinned layer yet without doing damage to the function of the synthetic pinned layer itself, viz., resistance to an external magnetic field.

A giant magneto-resistive effect device (GMR device) having a CPP (current perpendicular to plane) structure comprising a nonmagnetic spacer layer, and a fixed magnetized layer and a free layer stacked one upon another with said nonmagnetic spacer layer interleaved between them, with a sense current applied in a stacking direction, characterized in that:

said free layer functions such that a direction of magnetization changes depending on an external magnetic field, and
said fixed magnetization layer has a synthetic pinned morphology wherein an inner pin layer and an outer pin layer are stacked one upon another with a nonmagnetic intermediate layer held between them, said inner pin layer being located at a position nearer to said nonmagnetic spacer layer than to said outer pin layer, wherein:
a width W1 of said inner pin layer at a position tangent to said nonmagnetic spacer layer as viewed from a medium opposite plane is set at 50 nm or less,
said fixed magnetization layer has tapers at both ends as viewed from a medium opposite plane,
each of said tapers is tapered down to said non-magnetic spacer layer with the stacking direction of said device as a center axis direction, wherein a taper angle θ1 with respect to a reference line defined by a stacking plane as viewed from a medium opposite plane side is set in an angle range of 40° to 60°,
a magnetic volume ratio (Mso×V2)/(Msi×V1), represented by a ratio of (Mso×V2) that is a product of a saturation magnetization Mso and a volume V2 of said outer pin layer relative to (Msi×V1) that is a product of a saturation magnetization Msi and a volume V1 of said inner pin layer, lies in a range of 0.9 to 1.1, and
a magnetic thickness ratio (Mso×t2)/(Msi×t1), represented by a ratio of (Mso×t2) that is a product of a saturation magnetization Mso and a thickness t2 of said outer pin layer relative to (Msi×t1) that is a product of a saturation magnetization Msi and a thickness t1 of said inner pin layer, is set at 0.8 or less.

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Abstract

Claims12