The resistance of a magnetic tunnel junction (MTJ) depends on the
relative magnetization of the ferromagnetic layers such that it is low
in the parallel (P) configuration while it is high in the anti-parallel
(AP) one. The coherent tunneling is theoretically predicted to play a
central role in MTJs with the crystalline MgO barriers.
In this presentation, we report the shot noise measurement in
well-crystalline CoFeB/MgO/CoFeB-based MTJs with the increased
experimental accuracy. We observed reduced Fano factor (F~0.91) in P
configuration, while F in AP configuration was close to 1. Moreover,
this reduction is independent to the sample temperature and the
magnetic field.
Institute for Chemical Research, Kyoto University