US 8,133,363 B2Granted

Dual magnetic tunnel junction sensor with a longitudinal bias stack

AssigneeInternational Business Machines Corporation

InventorsTsann Lin, Daniele Mauri

Life of this patent

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Abstract

A dual magnetic tunnel junction (MTJ) sensor is provided with a longitudinal bias stack sandwiched between a first MTJ stack and a second MTJ stack. The longitudinal bias stack comprises an antiferromagnetic (AFM) layer sandwiched between first and second ferromagnetic layers. The first and second MTJ stacks comprise antiparallel (AP)-pinned layers pinned by AFM layers made of an AFM material having a higher blocking temperature than the AFM material of the bias stack allowing the AP-pinned layers to be pinned in a transverse direction and the bias stack to be pinned in a longitudinal direction. The demagnetizing fields of the two AP-pinned layers cancel each other and the bias stack provides flux closures for the sense layers of the first and second MTJ stacks.

Claims14

Dependent claims

A method of fabricating a dual magnetic tunnel junction (MTJ) sensor, the method comprising:

sputter depositing the multilayer dual MTJ sensor including a first magnetic tunnel junction (MTJ) stack having a first tunnel barrier layer, a second magnetic tunnel junction (MTJ) stack having a second tunnel barrier layer, and a longitudinal bias stack disposed between the first and second MTJ stacks;
annealing the dual MTJ sensor at a first temperature in a first magnetic field oriented in a transverse direction perpendicular to an air bearing surface for orienting a magnetization of at least one layer of each of the first and second MTJ stacks in a direction perpendicular to the air bearing surface;
and
annealing the dual MTJ sensor at a second temperature in a second magnetic field oriented in a longitudinal direction parallel to said air bearing surface for orienting a magnetization of at least one layer of the longitudinal bias stack in a direction parallel to the air bearing surface, wherein said second temperature is less than said first temperature and said second magnetic field has a magnitude smaller than said first magnetic field.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 10/981,926Filed 5 Nov 2004 · division
Priority: 2 Apr 2002
Published: US 2005/0061658 A124 Mar 2005
Granted: 13 Mar 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

G01R 33/093
Magnetoresistive devices: using multilayer structures, e.g. giant magnetoresistance sensors
B82Y 10/00
Nanotechnology for information processing, storage or transmission
B82Y 25/00
Nanomagnetism
G01R 33/098
Magnetoresistive devices: comprising tunnel junctions, e.g. tunnel magnetoresistance sensors

Family

Application10/116,017Parent of this division · filed 2 Apr 2002
US 2005/0061658 A1Pre-grant publication · published 24 Mar 2005
US 6,822,838 B2Parent of this division
US 2003/0184919 A1Published application
US 8,133,363 B2This patent

From the US filing history. Foreign family members aren’t listed.