Bistable magnetostrictive device
AssigneeInternational Business Machines Corporation
InventorDavid A. Thompson
Life of this patent
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Abstract
A device includes a core, such as a wire or cylinder of a solid material such as nonmagnetic metal, coated with a film of a material having a high degree of magnetostriction and a uniaxial helical magnetic anisotropy at an oblique angle to the longitudinal axis of the core. The device has the characteristic of being magnetically bistable and of providing a large magnetic pulse as it changes to one of its stable states in response to passage of a magnetic field by it. To achieve a helical magnetic anisotropy, the magnetostrictive film can be applied to a nonmagnetic wire by plating the wire while it is under torsion, twisting a plated wire after plating, or by applying an electric current and a magnetic field to the wire as the film is being plated or annealed.
Claims18
An elongated unitary magnetic device comprising
- first and second portions having dissimilar chemical compositions,
- at least said first portion being magnetostrictive and being capable of retaining net magnetization after being subjected to a magnetic field,
- the net coercivity of said first portion being substantially greater than the net coercivity of the second portion,
- said first and said second portions being separated along an interface of different composition providing a magnetic domain interface when said first portion has a net magnetization in a first direction and said second portion has a net magnetization substantially opposite from said first direction, and
- said first portion having a helical magnetic anisotropy about an axis along the overall length of said elongated device.
Dependencies are inferred from the claim text.