Study of magnetic properties and relaxation in amorphous Fe73.9Nb3.1Cu0.9Si13.2B8.9 thin films produced by ion beam sputtering

Amorphous Fe73.9Nb3.1Cu0.9Si13.2B8.9 thin films have been produced by ion beam sputtering with two different beam energies (500 and 1000 eV). Magnetic measurements indicate that the samples display a uniaxial magnetic anisotropy, especially for samples prepared with the lower beam energy. Magnetization relaxation has been measured on both films with an alternating gradient force magnetometer and magneto-optical Kerr effect. Magnetization relaxation occurs on time scales of tens of seconds and can be described with a single stretched exponential function. Relaxation intensity turns out to be higher when measured along the easy magnetization axis