Tunneling magnetoresistance (TMR) read sensor with a long diffusion path and ex-situ interfaces in a sense layer structure

摘要

The invention provides a tunneling magnetoresistance (TMR) read sensor with a long diffusion path and ex-situ interfaces in a sense layer structure. The sense layer structure comprises a first sense layer preferably formed of a ferromagnetic Co—Fe film, a second sense layer preferably formed of a ferromagnetic Co—Fe—B film, and a third sense layer preferably formed of a ferromagnetic Ni—Fe film. The sense layer structure has a long diffusion path (defined as a total thickness of the first and second sense layers) and ex-situ interfaces for suppressing unwanted diffusions of Ni atoms. Alternatively, the sense layer structure comprises a first sense layer preferably formed of a ferromagnetic Co—Fe film, a second sense layer preferably formed of a ferromagnetic Co—Fe—B film, a third sense layer preferably formed of a ferromagnetic Co—Fe—B—Hf film, and a fourth sense layer preferably formed of a ferromagnetic Ni—Fe film.

主权项

1. A read sensor, comprising:
a barrier layer sandwiched between a lower sensor stack and an upper sensor stack; the lower sensor stack comprising:
a pinning layer;a keeper layer structure on the pinning layer;an antiparallel-coupling layer on the keeper layer structure; anda reference layer structure on the antiparallel-coupling layer; the upper sensor stack comprising:
a sense layer structure that includes a first layer comprising CoFe formed on the barrier layer, a second layer consisting of CoFeB having a thickness of 2 to 4.8 nm and formed directly on the first layer and a third layer consisting of NiFe formed directly on the second layer, wherein the total thickness of the first sense layer and the second sense layer is large enough to form a sufficiently long diffusion path to trap Ni atoms thereby preventing Ni atoms from migrating from the third layer to the barrier layer; wherein the sense structure has a diffusion path (defined as the total thickness of the first and second sense layers) of at least 3.2 nm; and a cap layer structure on the sense layer structure.