| US 7,580,229 B2 | ||
| Current-perpendicular-to-the-plane (CPP) magnetoresistive sensor with antiparallel-free layer structure and low current-induced noise | ||
| Matthew J. Carey, San Jose, Calif. (US); Jeffrey R. Childress, San Jose, Calif. (US); Stefan Maat, San Jose, Calif. (US); and Neil Smith, San Jose, Calif. (US) | ||
| Assigned to Hitachi Global Storage Technologies Netherlands B.V., Amsterdam (Netherlands) | ||
| Filed on Apr. 27, 2006, as Appl. No. 11/380,625. | ||
| Prior Publication US 2007/0253119 A1, Nov. 01, 2007 | ||
| Int. Cl. G11B 5/39 (2006.01) | ||
| U.S. Cl. 360—324.12 | 21 Claims |
| 1. A magnetoresistive sensor having first and second electrical leads for connection to a current source that directs sense
current from the first lead to the second lead, the sensor having a stack of layers between the first and second leads comprising:
one and only one pinned ferromagnetic layer having an in-plane magnetization direction;
an antiparallel free (APF) structure consisting of a first free ferromagnetic layer (FL1) having an in-plane magnetization direction, a second free ferromagnetic layer (FL2) having an in-plane magnetization direction substantially antiparallel to the magnetization direction of FL1 and a magnetic moment less than that of FL1, and an AP coupling (APC) layer between and in contact with FL1 and FL2 and consisting essentially of a material selected from the group consisting of Ru, Ir, Rh and alloys thereof; and
an electrically conductive spacer layer between the pinned ferromagnetic layer and FL1 and consisting essentially of an element selected from the group consisting of Cu, Ag and Au, the pinned ferromagnetic layer
being located between the spacer layer and the first lead; and
wherein the sensor senses external magnetic fields in response to sense current applied perpendicular to the planes of the
layers in the sensor stack in a direction from the first lead to the pinned ferromagnetic layer to the spacer layer to the
APF structure and to the second lead.
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