Characteristics of Magnetic Tunnel Junctions Comprising Ferromagnetic Amorphous NiFeSiB Layers

Magnetic tunnel junctions (MTJs), which consisted of amorphous ferromagnetic NiFeSiB free layers, were investigated. The NiFeSiB layers were used to substitute for the traditionally used CoFe and/or NiFe layers with the emphasis being given to obtaining an understanding of the effect of the amorphous free layer on the switching characteristics of the MTJs. Ni16Fe62Si8B14 has a lower saturation magnetization (Ms: 800 emu/cm(3)) than Co90Fe10 and a higher anisotropy constant (K-u: 2,700 erg/cm(3)) than Ni80Fe20. The Si/ SiO 9/Ta 45/Ru 9.5/IrMn I 0/CoFe 7/AIOx/NiFeSiB t/Ru 60 (in nanometers) structure was found to be beneficial for the switching characteristics of the MTJ, leading to a reduction in the coercivity (H,) and an increase in the sensitivity resulted from its lower saturation magnetization and higher uniaxial anisotropy. Furthermore, by inserting a very thin CoFe layer at the tunnel barrieriNiFeSiB interface, the TMR ratio and switching squareness were improved more with the increase of NiFeSiB layer thickness up to 11 nm.