  We report on room temperature magnetoresistance and low frequency noise in
sub-100nm elliptic CoFeB/MgO/CoFeB magnetic tunnel junctions with ultrathin
(0.9nm) barriers. For magnetic fields applied along the hard axis, we observe
current induced magnetization switching between the antiparallel and parallel
alignments at DC current densities as low as 4*106A/cm2. We attribute the low
value of the critical current to the influence of localized reductions in the
tunnel barrier, which affects the current distribution. The analysis of random
telegraph noise, which appears in the field interval near a magnetization
switch, provides an estimate to the dimension of the pseudo pinholes that
trigger the magnetization switching via local spin torque. Micromagnetic
simulations qualitatively and quantitatively reproduce the main experimental
observations.
