Journal of the Korean Magnetics Society (한국자기학회지)

The Korean Magnetics Society (한국자기학회)
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Thermal Annealing Effect on Ferromagnetic Resonance Properties in CoFeB/MgO Thin Film

CoFeB/MgO 박막 재료의 열처리에 따른 강자성공명 특성

  • Received : 2010.12.14
  • Accepted : 2011.01.12
  • Published : 2011.02.28
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Abstract

We have measured the ferromagnetic resonance (FMR) signal in as deposited and $400^{\circ}C$ annealed CoFeB/MgO thin film to investigate the annealing effect on magnetic anisotropies and FMR linewidth (${\Delta}H_{PP}$). The uniaxial anisotropy field ($H_{K1}$) was only observed in the as deposited sample. Whereas, in the $400^{\circ}C$ annealed sample, the biaxial anisotropy field ($H_{K2}$) was additionally observed in accompany with uniaxial anisotropy field ($H_{K1}$). The appearance of biaxial anisotropy fields was originated from the crystalline growth of bcc CoFeB(001) from the MgO(001) interface and by the B diffusion during thermal annealing. Also, the ${\Delta}H_{PP}$ of $400^{\circ}C$ annealed sample was increased compared with that of as deposited sample, which was due to the broad distribution of the magnetization axis by the biaxial anisotropy.

본 연구에서는 열처리에 따른 자기이방성 자기장 및 강자성 공명 선폭(${\Delta}H_{PP}$) 변화 특성을 분석하기 위하여 열처리 전후의 CoFeB/MgO 박막 재료에 대하여 강자성 공명 신호를 측정하였다. 열처리 전에 일축이방성 자기장($H_{K1}$) 특성을 보이던 CoFeB는 열처리 후 쌍축이방성 자기장 ($H_{K2}$) 특성이 부가적으로 확연히 나타났다. 이는 비정질 CoFeB가 열처리에 의하여 B이 확산되는 과정에서 박막의 수평면에서 (001)결정면을 갖는 MgO 계면으로부터 CoFeB 역시 (001)결정면을 갖는 입방결정으로 성장하였기 때문이다. 또한 쌍축이방성을 갖는 결정축의 영향으로 수평면에서의 자화용이축의 분포 특성을 증가시켜 ${\Delta}H_{PP}$도 증가하는 특성을 보인다.

Keywords

References

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