Patents by Inventor Dennis Richard Wilhoit

Dennis Richard Wilhoit has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5701223
    Abstract: A spin valve magnetoresistive (SVMR) sensor uses a laminated antiparallel (AP) pinned layer in combination with an improved antiferromagnetic (AF) exchange biasing layer. The pinned layer comprises two ferromagnetic films separated by a nonmagnetic coupling film such that the magnetizations of the two ferromagnetic films are strongly coupled together antiferromagnetically in an antiparallel orientation. This laminated AP pinned layer is magnetically rigid in the small field excitations required to rotate the SVMR sensor's free layer. When the magnetic moments of the two ferromagnetic layers in this AP pinned layer are nearly the same, the net magnetic moment of the pinned layer is small. However, the exchange field is correspondingly large because it is inversely proportional to the net magnetic moment. The laminated AP pinned layer has its magnetization fixed or pinned by an AF material that is highly corrosion resistant but that has an exchange anisotropy too low to be usable in conventional SVMR sensors.
    Type: Grant
    Filed: August 23, 1996
    Date of Patent: December 23, 1997
    Assignee: International Business Machines Corporation
    Inventors: Robert Edward Fontana, Jr., Bruce Alvin Gurney, Tsann Lin, Virgil Simon Speriosu, Ching Hwa Tsang, Dennis Richard Wilhoit