Effect of deposition parameters on exchange bias studied using Lorentz and high-resolution electron microscopy

The effects of key deposition parameters on NiO-Py and NiMn-Py bilayers have been systematically investigated, which include the: 1) effect of annealing; 2) partial pressure of N₂ during permalloy deposition; and 3) presence or absence of Ta buffer layer. The 7% N₂ partial pressure induced (200) growth, whereas its absence during Ni₈₁Fe₁₉(Py) deposition induced (111) growth. The presence of Ta in conjunction with N₂ partial pressure controlled the growth and orientation of the exchange-bias layer. Lorentz microscopy was used to investigate the magnetic-domain reversal mechanisms and a high-resolution electron microscopy was used to correlate microstructure with magnetic behavior.