US 2006/0221509 A1Published application

Magnetoresistive sensor based on spin accumulation effect with free layer stabilized by in-stack orthogonal magnetic coupling

AssigneeHitachi Global Storage Technologies Netherlands B.V.

InventorsMatthew Carey, Jeffrey Childress, Stefan Maat

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Abstract

A magnetoresistive sensor based on the spin accumulation effect has an in-stack biasing structure with a ferromagnetic biasing layer that is magnetically-coupled orthogonally with the sensor free ferromagnetic layer across a spacer layer. The sensor has an electrically conductive strip with a first tunnel barrier and a free ferromagnetic layer on the front or sensing end of the strip and second tunnel barrier and a fixed ferromagnetic layer on the back end of the strip. A magnetically-coupling spacer layer is formed on the free layer and the ferromagnetic biasing layer is formed on the spacer layer. The magnetically-coupling layer induces direct orthogonal magnetic coupling between the in-plane magnetization directions of the biasing layer and the free layer.

Claims22

Dependent claims

A magnetoresistive sensor capable of sensing external magnetic fields comprising:

a substrate;
an electrically conductive strip on the substrate and having first and second ends;
a first tunnel barrier on the strip at the first end;
a free ferromagnetic layer on the first tunnel barrier and having an in-plane magnetization direction oriented substantially in a first direction in the absence of an external magnetic field, said free layer magnetization direction being substantially free to rotate in the presence of an external magnetic field;
a ferromagnetic biasing layer magnetically-coupled to the free layer and having an in-plane magnetization direction oriented substantially orthogonal to said first direction in the absence of an external magnetic field;
and
a spacer layer between the biasing and free layers, the spacer layer between the biasing and free layers inducing substantial orthogonal magnetic coupling of the free layer to the biasing layer;
a second tunnel barrier on the strip at the second end;
and
a fixed ferromagnetic layer on the second tunnel barrier and having an in-plane magnetization direction oriented in a second direction substantially orthogonal to said first direction and substantially prevented from rotation in the presence of an applied magnetic field in the range of interest.

7 more elements

A magnetoresistive read head for reading magnetically recorded data from tracks on a magnetic recording medium, the head comprising:

a substrate;
a first shield of magnetically permeable material on the substrate and having a substantially horizontal planar surface;
an electrically conductive strip on the substrate and having a sensing end and a back end;
a first tunnel barrier on the strip at the sensing end;
a free ferromagnetic layer on the first tunnel barrier and having an in-plane magnetization direction oriented substantially in a first direction in the absence of an external magnetic field, said free layer magnetization direction being substantially free to rotate in the presence of an external magnetic field from the recording medium;
a ferromagnetic biasing layer magnetically-coupled to the free layer and having an in-plane magnetization direction oriented substantially orthogonal to said first direction in the absence of an external magnetic field;
a magnetically-coupling layer between the biasing and free layers, the magnetically-coupling layer between the biasing and free layers inducing substantial orthogonal magnetic coupling of the free layer to the biasing layer;
a second tunnel barrier on the strip at the second end;
a pinned ferromagnetic layer on the second tunnel barrier and having an in-plane magnetization direction oriented in a second direction substantially orthogonal to said first direction and substantially prevented from rotation in the presence of a magnetic field from the recording medium;
circuitry connected to the pinned layer and the second end of the strip for passing electrical current through the pinned layer and the second tunnel barrier into the second end of the strip;
and
electrical-resistance-detecting circuitry connected to the free layer and the first end of the strip for detecting changes in electrical resistance across the first tunnel barrier in response to external magnetic fields from the recording medium when current is passing at the second end of the strip.

9 more elements

Dependencies are inferred from the claim text.