Characterization of a Nano-Oxide Layer in a Pseudo Spin Valve by Complex Magneto-Impedance Spectroscopy

The ac properties of a pseudo spin valve (PSV) consisting of NOL
_top
/Co/Cu/Co/Ni
₈₀
Fe
₂₀
/NOL
_bottom
with a top and bottom nano-oxide layer (NOL) were studied as functions of NOL and thickness, d, by magneto impedance spectroscopy. The NOLs were formed by natural oxidizing the top and bottom ferromagnetic or Ta layers in situ. The increase in the thickness of NOL resulting in the increment of effective capacitance caused the shift of roll-off frequency from low to high. The frequency dependence behavior of this NOL
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/PSV/NOL
_bottom
system can be modeled by equivalent circuit theory. PSV with a different NOL structure can be checked by such a nondestructive analysis method