Interfacial Perpendicular Magnetic Anisotropy in Magnetic Tunnel Junctions Comprising CoFeB with FeNiSiB Layers

  • Do Kyun Kim
  • Minhyeok Lee
  • Junghoon Joo
  • Young Keun KimEmail author
Original Article - Electronics, Magnetics and Photonics


Controlling ferromagnetic thickness (t) and properties such as saturation magnetization (Ms) and effective magnetic anisotropy constant (Keff) has been regarded as critical for the performance of magnetic tunnel junctions (MTJs) with interfacial perpendicular magnetic anisotropy. Here, we report the effects of hybridizing a CoFeB layer with a FeNiSiB layer as part of a magnetic free layer structure. We deposited thin film stacks by magnetron sputtering on Si wafers with thermal oxides and carried out post-deposition heat treatment at 300 °C for 1 h in a vacuum under a magnetic field. We found that Ms and Keff could be tuned by adding a layer of amorphous FeNiSiB. While the Ms and Keff values were modified, the tunneling magnetoresistance (TMR) ratios of the MTJs were maintained, even though the CoFeB thickness was decreased by half. Moreover, an asymmetric bias voltage dependence of TMR was suppressed in the MTJs with FeNiSiB/CoFeB hybrid free layers due to improvements in the interface quality between the CoFeB/MgO interfaces.

Graphic Abstract


Perpendicular magnetic anisotropy Magnetic tunnel junction Hybrid free layer CoFeB FeNiSiB 



This work was supported in part by the Future Materials Discovery Program through the National Research Foundation of Korea, funded by the Ministry of Science and ICT (Grant No. 2015M3D1A1070465), by the Samsung Electronics’ University R&D program.


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Copyright information

© The Korean Institute of Metals and Materials 2019

Authors and Affiliations

  1. 1.Department of Materials Science and EngineeringKorea UniversitySeoulKorea
  2. 2.Department of Materials Science and EngineeringKunsan National UniversityKunsan-siKorea

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