Magnetic field sensor and magnetic disk apparatus

A magnetic field sensor, comprising:

• a pair of magnetic shields arranged apart from each other with a gap and serving as a negative electrode and a positive electrode, respectively;
• a magnetoresistive element arranged between the pair of magnetic shields and including a magnetization free layer, a nonmagnetic intermediate layer, a magnetization pinned layer, and an antiferromagnetic layer, the antiferromagnetic layer being formed in direct contact with the magnetic shield for the positive electrode;
• and
• a nonmagnetic conductive layer for the negative electrode arranged between the magnetic shield for the negative electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, and the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu.

A magnetic field sensor comprising:

• a pair of magnetic shields arranged apart from each other with a gap and serving as a negative electrode and a positive electrode, respectively;
• a magnetoresistive element arranged between the pair of magnetic shields and including a magnetization free layer, a nonmagnetic intermediate layer, a magnetization pinned layer, and an antiferromagnetic layer;
• a nonmagnetic conductive layer for the negative electrode arranged between the magnetic shield for the negative electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, and the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu;
• and
• a nonmagnetic conductive layer for the positive electrode arranged between the magnetic shield for the positive electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu, and the thickness of the first metal layer being 1 nm or less and the thickness of the second metal layer being not greater than that of the first metal layer.

A magnetic field sensor, comprising:

• a pair of magnetic shields arranged apart from each other with a gap and serving as a negative electrode and a positive electrode, respectively;
• a magnetoresistive element arranged between the pair of magnetic shields and including a magnetization free layer, a nonmagnetic intermediate layer, a magnetization pinned layer, and an antiferromagnetic layer;
• a nonmagnetic conductive layer for the negative electrode arranged between the magnetic shield for the negative electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, and the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu;
• and
• a nonmagnetic conductive layer for the positive electrode arranged between the magnetic shield for the positive electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu, and the thickness of the first metal layer falling within a range of between 1 nm and 10 nm and the thickness of the second metal layer being not greater than the square of the thickness of the first metal layer divided by two.

A magnetic field sensor, comprising:

• a pair of magnetic shields arranged apart from each other with a gap and serving as a negative electrode and a positive electrode, respectively;
• a magnetoresistive element arranged between the pair of magnetic shields and including a magnetization free layer, a nonmagnetic intermediate layer, a magnetization pinned layer, and an antiferromagnetic layer;
• a nonmagnetic conductive layer for the negative electrode arranged between the magnetic shield for the negative electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, and the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu;
• and
• a nonmagnetic conductive layer for the positive electrode arranged between the magnetic shield for the positive electrode and the magnetoresistive element and including a first metal layer formed in contact with the magnetoresistive element and a second metal layer formed in contact with the first metal layer, the first metal layer containing at least one metal selected from the group consisting of Ta, Ti, Cr, V, Mo and W, the second metal layer containing at least one metal selected from the group consisting of Au, Ag and Cu, and the thickness of the first metal layer being 10 nm or more.