Magnetic switching properties of Fe-Ni-Pt thin films with graded magnetocrystalline anisotropy

Exchange-coupled composites and graded magnetocrystalline anisotropy
Ku
films allow a lower switching field while maintaining a given thermal stability relative to a conventional single
Ku
thin film. In this letter, [001] oriented single composition, multilayered single compositions, and a linearly graded composition of
L
1
₀
Fe
x
Ni
_0.48-
x
Pt
_0.52
thin films were sputter-deposited. The films were patterned into an array of ~70-80 nm diameter nanodots by electron beam lithography and Ar ion etching. A relative improvement in the switching field-to-thermal stability of ~41% was achieved for the continuous graded film as compared to the single composition Fe
_0.23
Ni
_0.25
Pt
_0.52
film. However, the patterned diameter size was still too large to prevent lateral magnetic domain wall motion; consequently, the absolute switching field-to-thermal stability value was low.