Magnetic noise measurements using cross-correlated Hall sensor arrays

An experimental technique for measuring magnetic fluctuations by means of a double-layer Hall sensor array is described. The technique relies on cross -correlating Hall signals from two independent sensors positioned one above the other in two separate two-dimensional-electron-gas layers of a GaAs/Al GaAs heterostructure. The effectiveness of the technique is demonstrated by a reduction of the magnitude of the background noise floor of the correlat ed sensors with respect to the noise level of the best single sensor. (C) 2 001 American Institute of Physics.