Magnetic exchange bias enhancement through seed layer variation in FeMn/NiFe layered structures

Abstract The exchange bias and crystalline texture of the multilayer structure (Ta/Al/seed/Fe 50 Mn 50 /Ni 81 Fe 19 /Al 2 O 3 /Ni 81 Fe 19 /Al/Ta with seed=Ni 81 Fe 19 or Ni 81 Fe 19 /Cu) has been characterized. Measurements indicate an abrupt decrease in exchange bias of the Ni 81 Fe 19 pinned layer for samples with very thin seed layers, and exchange bias as high as 325 Oe for thicker seed layers. Fluctuation of exchange bias with thickness was greatly reduced for the Ni 81 Fe 19 /Cu seed configuration. X-ray diffraction measurements demonstrate a correlation between exchange bias and strong (1 1 1) texture of FeMn. The results suggest a high sensitivity of Ni 81 Fe 19 roughness and texture on deposition conditions, and corroborate previous observations of roughness in ultrathin NiFe films.