Probing momentum distributions in magnetic tunnel junctions via hot-electron decay

The tunnel momentum distribution in a (magnetic) tunnel junction is probed by analyzing the decay of the hot electrons in the Co metal anode after tunneling, using a three-terminal transistor structure in which the hot-electron attenuation is sensitive to the tunnel momentum distribution. Solid state amorphous Al2O3 barriers and the vacuum barrier of a scanning tunneling microscope are compared. For the former the attenuation length in nominally the same Co is strikingly larger (factor of 2), implying a more isotropic tunnel momentum distribution for Al2O3 barriers.