Magnetoresistive sensor with random crystal orientation underlayer and magnetic domain control film center aligned with free layer
View Patent ↗In a magnetoresistive head according to the present invention, a magnetic domain control film formed at the end of a free layer of a stack of magnetoresistive layers is formed of a Co alloy film, and an underlayer controlling the crystallization state of the Co alloy film and an amorphous metal film layer for controlling the crystallization state of the underlayer are disposed below the magnetic domain control film.
1. A magnetoresistive sensor comprising:
a magnetoresistive stack layer including a first anti-ferromagnetic layer, a first pinned layer, a first non-magnetic layer, and a free layer;
a first underlayer of said magnetoresistive stack layer;
a magnetic domain control film; and
a pair of electrode films for supplying current to said magnetoresistive stack layer;
a second underlayer formed below said magnetic domain control film; and
an amorphous metal film layer formed below said second underlayer for controlling a crystallization of said second underlayer,
wherein a center position of an upper surface and a lower surface of said magnetic domain control film is positioned within a range of an upper surface and a lower surface of said free layer, and
wherein said second underlayer is formed of Cr or Cr alloy and comprises a body-centered cubic lattice (BCC) polycrystal thin film, and polycrystal orientation of said second underlayer against a formed plane thereof is isometric random crystal orientation having no particular crystal orientation.
2. A magnetoresistive sensor according to claim 1 ,
wherein said magnetoresistive stack layer further comprises a protection layer, and
wherein said first underlayer, said first anti-ferromagnetic layer, said first pinned layer, said first non-magnetic layer, said free layer and said protection layer are formed in order.
3. A magnetoresistive sensor according to claim 1 , wherein said amorphous metal film layer is formed on any one of surfaces within a range from a lower surface of said second underlayer to an upper surface of said first non-magnetic layer.
4. A magnetoresistive sensor according to claim 1 , wherein a lower surface of said free layer is aligned with a lower surface of said magnetic domain control film, and a bias magnetic field of said magnetic domain control film is mainly applied to said free layer.
5. A magnetoresistive sensor according to claim 1 , wherein said magnetic domain control film is formed of a Co alloy film, said second underlayer controls a crystallization state of said magnetic domain control film, and said amorphous metal film layer controls a crystallization state of said second underlayer.
6. A magnetoresistive sensor according to claim 1 , wherein said magnetic domain control film is formed of a Co alloy film, said second underlayer is formed of a Cr or Cr alloy film, and said amorphous metal film layer is formed of an Ni series alloy or Co series alloy film.
7. A magnetoresistive head constituted by using a magnetoresistive sensor according to claim 1 .