Low frequency noise in arrays of magnetic tunnel junctions connected in series and parallel

Low frequency noise and small output voltage are the strongest limitations to the use of magnetic tunnel junctions (MTJs) for magnetic sensor applications, replacing giant magnetoresistance (GMR) and anisotropic magnetoresistance sensors. In this paper, we explore the possibility of using arrays with a large number of MTJs connected in parallel/series to overcome these limitations. MTJ's sensor arrays of more than 3 x 10(3) junction elements in different configurations have been fabricated. Low frequency noise and detectivity have been measured and compared to an analytical model, with detectivities of about 16 nT/Hz(1/2) achieved in a series/parallel architecture. This detectivity levels are competitive with single devices based on GMR, with the advantage of not requiring additional flux concentrators. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3139284]