Low-frequency noise and tunneling magnetoresistance in Fe(110)/MgO(111)/Fe(110) epitaxial magnetic tunnel junctions

Guerrero R, Aliev FG, Villar R, et al. Low-frequency noise and tunneling magnetoresistance in Fe(110)/MgO(111)/Fe(110) epitaxial magnetic tunnel junctions. APPLIED PHYSICS LETTERS. 2005;87(4): 042501.We report on tunneling magnetoresistance (TMR), current-voltage (I-V) characteristics and low-frequency noise in epitaxially grown Fe(110)/MgO(111)/Fe(110) magnetic tunnel junctions (MTJs) with dimensions from 2x2 to 20x20 mu m(2). The evaluated MgO energy barrier (0.50 +/- 0.08 eV), the barrier width (13.1 +/- 0.5 angstrom) as well as the resistance times area product (7 +/- 1 M Omega mu m(2)) show relatively small variation, confirming a high quality epitaxy and uniformity of all MTJs studied. The noise power, though exhibiting large variation, was observed to be roughly anticorrelated with the TMR. Surprisingly, for the largest junctions we observed a strong enhancement of the normalized low-frequency noise in the antiparallel magnetic configuration. This behavior could be related to an interplay between the magnetic state and the local barrier defects structure of the epitaxial MTJs. (c) 2005 American Institute of Physics