Hybrid magnetoresistive∕microelectromechanical devices for static field modulation and sensor 1∕f noise cancellation

Abstract

Low frequency 1∕f noise in magnetoresistive (MR) spin valve sensors was suppressed by modulating an external dc magnetic field at high frequency microelectromechanical system using a (MEMS) microcantilever structure with an integrated magnetic flux guide. With this hybrid MR∕MEMS device, direct detection of dc magnetic fields in the sensor high frequency thermal noise regime was achieved. The microcantilever was actuated using a gate electrode by applying an ac voltage with frequency f, causing it to oscillate at 2f. Measurements show detection of a dc magnetic field at 2f frequency (400kHz), where sensor 1∕f noise is two orders of magnitude lower than dc.