Magnetic and magnetoelastic properties of cobalt–iron amorphous–nanocrystalline pulsed laser deposited thin films

We prepared pulsed laser deposited planar and cylindrical amorphous–nanocrystalline Co–Fe thin films using the corresponding target with composition Co1−xFex, x=0,0.02,…,1.0. Their room temperature spontaneous magnetization, Ms (film), was always a fraction of the Ms of the corresponding crystalline alloy, Ms (film)=γ Ms (crystal): γ≈0.8 for pure Co, γ≈0.88 for the Co35Fe65 film and γ≈0.94 for pure Fe. Their isotropic magnetostriction coefficient, λs, was also determined. From pure Co to 30at.% Fe λs values were similar to those corresponding to the crystalline alloys: from pure Co to 4 at.% Fe was negative and of the order of 10−6; λs increased to 10−5 up to 25 at.% Fe and achieved 10−4 from 30 at.% Fe to 90 at.% Fe; λs decreased to 10−5 for pure Fe. A chemical short-range order between the Co atoms surrounded by the Fe ones, increasing the magnetic moment of Fe atoms, was used to explain the observed behavior.