FeCoB Films with Large Saturation Magnetization and High Magnetic Anisotropy Field to Attain High Ferromagnetic Resonance Frequency

  • Nakagawa, Shigeki (Department of Physical Electronics, Tokyo Institute of Technology) ;
  • Hirata, Ken-Ichiro (Department of Physical Electronics, Tokyo Institute of Technology)
  • Received : 2012.05.31
  • Accepted : 2012.09.11
  • Published : 2013.06.30


FeCoB films were being prepared on a Ru underlayer by using the oblique incidence of sputtered and back-scattered particles which have a high in-plane magnetic anisotropy field $H_k$ above 400 Oe. It is suitable to attain such deposition condition when facing targets sputtering system. The in-plane X-ray diffraction analysis clarified that there is anisotropic residual stress which is the origin of the high in-plane magnetic anisotropy. The directional crystalline alignment and inclination of crystallite growth were also observed. Such anisotropic crystalline structures may affect the anisotropic residual stress in the films. The B content of 5.6 at.% was appropriate to induce such anisotropic residual stress and $H_k$ of 410 Oe in this experiment. The film with B content of 6 at.% possessed large saturation magnetization of 22 kG and high $H_k$ of 500 Oe. The film exhibited high ferromagnetic resonance frequency of 9.2 GHz.


FeCoB;high magnetic anisotropy field;anisotropic residual stress;ferromagnetic resonance frequency


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