The low frequency noise in magnetic tunnel junctions was studied as a function of applied magnetic field. In magnetic states where the magnetization is reversing, the measurement indicates a 1/ f2 spectrum whereas at all other applied fields a 1/f spectrum is observed. The 1/ f2 spectra are found to be an artifact of the magnetic after effect. Without the artificial influence of the magnetic after effect, only 1/f spectra are observed.
Bibliographical noteFunding Information:
We would like to acknowledge useful conversations with Randall Victora and that this work was supported primarily by the MRSEC Program of the National Science Foundation under Award Nos. DMR-0212302 and DMR-0819885.