International Business Machines Corporation

Omar U Need, Iii

Wayne Martin Moreau

Edward Gipstein

Bruce Alvin Gurney

Virgil S Speriosu

Dennis R Wilhoit

Haralambos Lefakis

Stuart Stephen Parkin

David Eugene Heim

A magnetoresistive read sensor based on the spin valve effect in which a component of the read element resistance varies as the cosine of the angle between the magnetization directions in two adjacent magnetic layers is described. The sensor read element includes two adjacent ferromagnetic layers separated by a nonmagnetic metallic layer. A layer of nonmagnetic electrically conductive material is deposited adjacent to and in contact with one of the ferromagnetic layers, referred to as a filter layers to form a back or conduction layer which provides a low resistance path for conduction electrons transmitted through the adjacent filter layer. The thickness of the filter layer is selected such that it effectively blocks conduction electrons having spins antiparallel to the direction of magnetization in the filter layer while allowing conduction electrons with parallel spins to be transmitted through the layer into the adjacent back layer. The magnetization of the filter layer is free to rotate in response to an applied magnetic field thereby effectively varying the electrically resistance to conduction electrons in the back/filter layer. The thickness of the back layer is selected to optimize the sensor parameters being measured and is in a range of about 4.0 A to 1000 A.

Magnetoresistive spin valve sensor having a nonmagnetic back layer

A magnetic recording data storage system of high recording density is made possible by an improved magnetoresistive sensor. The sensor has a ferromagnetic sensing layer that is a laminated layer of two ferromagnetic films antiferromagnetically coupled to one another and separated by an antiferromagnetically coupling film. By appropriate selection of the thickness of the nonmagnetic antiferromagnetically coupling film, the ferromagnetic films become antiferromagnetically coupled and their magnetizations rotate as a single rigid unit in the presence of the external magnetic field to be sensed. The ferromagnetic sensing layer can be used in conventional magnetoresistive sensors of the anisotropic magnetoresistive (AMR) type and in spin valve magnetoresistive (SVMR) sensors. In the spin valve sensor, the laminated ferromagnetic sensing layer serves as the free layer and is preferably formed of two films of nickel-iron (Ni-Fe) separated by a ruthenium (Ru) antiferromagnetically coupling film. Because the two ferromagnetic films have their moments aligned antiparallel, then, assuming the two films are made of the same material, by selecting the two films to have different thicknesses the effective free layer thickness can be reduced without significantly reducing the magnetoresistance.

Magnetoresistive sensor with improved ferromagnetic sensing layer and

A positive resist image is produced by exposure of a layer of non-crosslinked polymeric material to high energy radiation in a predetermined pattern, the polymeric material containing alkyl methacrylate units and polymerized units of certain other ethylenically unsaturated monomers, followed by removal of the electron degraded material from the exposed areas.

Preparation of resist image with methacrylate polymers

Very sensitive electron beam positive resists have been obtained using films of nitrocellulose containing 10.5 to 12% nitrogen.

Use of nitrocellulose containing 10.5 to 12% nitrogen as electron beam

Electron beam positive resists which are sensitive to electron beam radiation and simultaneously thermally stable are prepared using polycarbonates.

Thermally stable positive polycarbonate electron beam resists

Very sensitive electron beam positive resists have been obtained using films of polymeric methyl methacrylate containing acetate polymers.

Growing community of inventors

San Jose, CA, United States of America

Omar U Need, Iii