High Magnetic Anisotropy Field in CoZr Thin Films

Magnetic properties and high frequency characteristics of Co
_100-x
Zr
_x
(x=5-17) thin films have been investigated. The experimental results show that with the increase of Zr content, the saturation magnetization, 4πM
_s
, decreases from 12.3 kG for x=5 to 7.3 kG for x=17; induced anisotropic field, H
_k
, of the films increases from 232 Oe for x=5 at first and reaches a maximum value of 266 Oe for x=9; coercivive force along hard and easy direction, H
_ch
and H
_ce
, ranges 1.6-7.1 Oe and 5.4-10.9 Oe, respectively. The highest ferromagnetic resonance frequency,
f
_FMR
of 4.9 GHz could be achieved for the films with x=9. In addition, H
_ch
and H
_ce
are reduced by adopting Cu underlayer or Ni
₂₀
Fe
₈₀
underlayer to the studied CoZr films. The optimal magnetic properties of 4πM
_s
=12 kG , H
_ce
=5.4 Oe, H
_ch
=0.7 Oe, H
_k
=258 Oe , ρ = 233 μΩ-cm and
f
_FMR
=5 GHz are obtained for Co
₉₁
Zr
₉
(110 nm)/Ni
₂₀
Fe
₈₀
(15 nm) bilayer.