  We report on room temperature 1/f noise in fully epitaxial
Fe(45nm)/MgO(2.6nm)/Fe(10nm) magnetic tunnel junctions (MTJs) with and without
carbon doping of the Fe/MgO bottom interface. We have found that the normalized
noise (Hooge factor) asymmetry between parallel and antiparallel states may
strongly depend on the applied bias and its polarity. Both types of MTJs
exhibit record low Hooge factors being at least one order of magnitude smaller
than previously reported.
