The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 09, 2013
Filed:
Aug. 07, 2008
Matthew J. Carey, San Jose, CA (US);
Jeffrey R. Childress, San Jose, CA (US);
Stefan Maat, San Jose, CA (US);
Matthew J. Carey, San Jose, CA (US);
Jeffrey R. Childress, San Jose, CA (US);
Stefan Maat, San Jose, CA (US);
HGST Netherlands B.V., Amsterdam, NL;
Abstract
A magnetic field sensing system with a current-perpendicular-to-the-plane (CPP) sensor, like that used for giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR) spin-valve (SV) sensors, operates in a mode different from conventional GMR-SV and TMR-SV systems. An alternating-current (AC) source operates at a fixed selected frequency and directs AC perpendicularly through the layers of the CPP sensor, with the AC amplitude being high enough to deliberately induce a spin-torque in the CPP sensor's free layer. The AC-induced spin-torque at the selected frequency causes oscillations in the magnetization of the free layer that give rise to a DC voltage signal V. Vis a direct result of only the oscillations induced in the free layer. The value of Vwill change in response to the magnitude of the external magnetic field being sensed and as the free layer is driven in and out of resonance with the AC.