Methods for measuring magnetostriction in magnetoresistive elements
AssigneeInternational Business Machines Corporation
InventorHubert Grimm
Life of this patent
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Abstract
A system for directly measuring a magnetostriction value of a magnetoresistive element includes a fixture for receiving a substrate carrying one or more magnetoresistive elements. A magnet assembly applies a first magnetic field parallel to the substrate, and a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements. A stress-inducing mechanism applies a mechanical stress to the substrate, the stress being oriented parallel to the substrate. A measuring subsystem measures a signal from at least one of the magnetoresistive elements.
Claims25
A system for directly measuring a magnetostriction value of a magnetoresistive element, the system comprising:
- a fixture for receiving a substrate carrying one or more magnetoresistive elements;
- a magnet assembly for applying a first magnetic field parallel to the substrate, and for applying a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements;
- a mechanism for applying a mechanical stress to the substrate, the stress being oriented parallel to the substrate;
- and
- a measuring subsystem for measuring a signal from at least one of the magnetoresistive elements.
A system for directly measuring a magnetostriction value of a magnetoresistive element, the system comprising:
- a bending fixture for receiving a substrate carrying one or more magnetoresistive elements;
- a magnet assembly for applying a magnetic direct current (DC) field parallel to the substrate, and for applying a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements;
- a mechanism for applying a mechanical stress to the substrate by bending the substrate, the stress being oriented parallel to the substrate;
- a control circuit for changing the DC magnetic field;
- and
- a measuring subsystem for measuring a signal from at least one of the magnetoresistive elements prior to application of the mechanical stress, after application of the mechanical stress, and during a time period when the DC magnetic field is changed.
A system for directly measuring a magnetostriction value of a magnetoresistive element, the system comprising:
- a bending fixture for receiving a substrate carrying one or more magnetoresistive elements;
- a magnet assembly for applying a magnetic direct current (DC) field parallel to the substrate, and for applying a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements;
- a DC power supply for providing power to the magnet assembly;
- an alternating current (AC) power supply for providing power to the magnet assembly;
- a mechanism for applying a mechanical stress to the substrate by bending the substrate, the stress being oriented parallel to the substrate;
- a measuring subsystem for measuring a signal from at least one of the magnetoresistive elements prior to application of the mechanical stress, after application of the mechanical stress, and during a time period when the DC magnetic field is changed;
- a control circuit for changing the DC magnetic field until the signal currently being measured by the measuring subsystem about matches a signal measured before applying the mechanical stress;
- and
- a computing device for calculating a magnetostriction constant of the at least one magnetoresistive element based in part on a change of mechanical stress anisotropy due to application of the mechanical stress and the change in the DC magnetic field.
A method for directly measuring a magnetostriction value of a magnetoresistive element, the method comprising:
- providing a substrate carrying one or more magnetoresistive elements;
- placing the substrate on a fixture;
- applying a first magnetic field parallel to the substrate;
- applying a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements;
- measuring a signal from the element;
- applying a mechanical stress to the substrate, the stress being oriented parallel to the substrate;
- and
- changing the first magnetic field until the signal currently being measured about matches a signal measured before applying the mechanical stress.
A method for directly measuring a magnetostriction value of a magnetoresistive element, the method comprising:
- providing a substrate carrying one or more magnetoresistive elements;
- placing the substrate on a bending fixture;
- applying a magnetic DC field parallel to the substrate;
- applying a magnetic alternating field perpendicular to the substrate and parallel to magnetoresistive layers of the elements;
- measuring a signal from at least one element;
- applying a mechanical stress to the substrate by bending the substrate, the stress being oriented parallel to the substrate;
- changing the magnetic DC field until the signal currently being measured about matches a signal measured before applying the mechanical stress;
- and
- calculating a magnetostriction value of the element.
Dependencies are inferred from the claim text.