Abstract
High tunneling magnetoresistance ratios (TMR) up to 44.6% were observed at room temperature on magnetic tunnel junctions (MTJs) with Ta20/Ni
81Fe
1920/Co
90Fe
102/Al(1
nm)-oxide/Co
90Fe
102/Ni
81Fe
197/Fe
50Mn
5020/Ta5 (the thickness of other layers is in nm) structures fabricated by using an inductively coupled plasma sputtering system operating at a base pressure of 5×10
−10
Torr. High field sensitivity up to 6.1%/Oe has been achieved in these MTJs with dimensions of 120
μm×120
μm by using extremely soft ferromagnetic (FM) Ni
81Fe
19/Co
90Fe
10 electrode. Small ferromagnetic coupling field (11
Oe) between the top and bottom FM electrodes, high breakdown electrical field (1.2×10
7
V/cm), and high
V
h (340–414
mV) at which the TMR decreases to 50% of its initial value, were obtained as the surface roughness of the bottom FM electrode (
R
ms
<3
A
̊
) and Al-oxide (
R
ms
<1
A
̊
) layer have been improved.