U. May et al., Temperature-dependent magnetoresistance of magnetic tunnel junctions with ultraviolet light-assisted oxidized barriers, APPL PHYS L, 78(14), 2001, pp. 2026-2028
Co(10 nm)/AlOx(nominally 2 nm)/Co(20 nm) tunnel junctions have been prepare
d under ultrahigh vacuum conditions applying a shadow mask technique. An ul
traviolet light-assisted oxidation process of the AlOx barrier has been opt
imized by in situ x-ray photoelectron spectroscopy, in conjunction with tem
perature-dependent tunneling magnetoresistance measurements. Optimum-oxidiz
ed tunnel junctions show a magnetoresistance of 20% at 285 K, and up to 38%
at 100 K. For under-oxidized samples, with a remaining Al layer between th
e Co bottom electrode and the AlOx barrier, the tunneling magnetoresistance
decreases more rapidly with increasing temperature than observed for the o
ver-oxidized samples. The resistance x area product of optimum-oxidized tun
neling junctions exhibits a minimum, and increases for under- and over-oxid
ized samples. (C) 2001 American Institute of Physics.