Structure and magnetism of nanocrystalline exchange-coupled (Ni0.67Co0.25Fe0.08)89−xZr7B4Cux (x=,1) films

Structural and magnetic characterizations of nanocrystalline films of (Ni0.67Co0.25Fe0.08)89−xZr7B4Cux (x=0,1) alloys are reported. The films were grown on quartz substrates using pulsed laser deposition from homogeneous targets of the above compositions at substrate temperatures ranging from ambient to 600°C. Structural properties were measured by x-ray diffraction, atomic force microscopy, and transmission electron microscopy, whereas the magnetic properties were measured by vibrating sample magnetometry and ferromagnetic resonance. The resulting films exist as a two phase alloy with face-centered-cubic metallic grains suspended in an amorphous matrix. For both the x=1 and x=0 alloys, the softest magnetic properties (coercivity Hc<0.5Oe, 4πMs∼7000G) coincided to a deposition at 300°C in which the fcc grain size (D) was 6–8nm separated by an amorphous phase of ∼1nm. At higher substrate temperatures (Ts) grain size follow a Ts2 dependence, while at lower temperatures the grain size is comparable but the v...