Magnetization switching and tunneling magnetoresistance effects of synthetic antiferromagnet free layers consisting of amorphous NiFeSiB

Byong Sun Chun, Ilsang Yoo, Young-geun Kim, Jae Youn Hwang, Jang Roh Rhee, Taewan Kim, Wanjun Park

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Abstract

A synthetic antiferromagnet (SAF) structure comprising of ferromagnetic amorphous Ni16 Fe62 Si8 B14 layers has been devised and employed as a free layer of magnetic tunnel junctions (MTJs) to enhance cell switching performance. We observed -0.03 erg cm2 of exchange coupling energy (Jex) by inserting a 0.5 nm Ru layer in between NiFeSiB layers. In Si SiO2 Ta 45Ru 9.5IrMn 10CoFe 7 AlOx 1.5 (single NiFeSiB 7) or [NiFeSiB (t) Ru 0.5NiFeSiB (7-t)] Ru 60 (nm) MTJ structures, we found size dependence of the switching field originating from the lower Jex both experimentally and by simulation. The NiFeSiB SAF structure showed lower switching field than traditional CoFe and CoFeB SAF structures. This is because NiFeSiB possesses low saturation magnetization (Ms =800 emu cm3) and high anisotropy constant (Ku =2,700 erg cm3). These properties were proven beneficial for the switching characteristics such as reducing the coercivity (Hc) and increasing the sensitivity in micrometer to submicrometer sized elements.

Original languageEnglish
Article number082508
JournalApplied Physics Letters
Volume87
Issue number8
DOIs
Publication statusPublished - 2005 Aug 22

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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