Multi-jump magnetic switching in ion-beam sputtered amorphous Co20Fe60B20 thin films

Unconventional multi-jump magnetization reversal and significant in-plane uniaxial magnetic anisotropy (UMA) in the ion-beam sputtered amorphous Co20Fe60B20(5-75 nm) thin films grown on Si/amorphous SiO2 are reported. While such multi-jump behavior is observed in CoFeB(10 nm) film when the magnetic field is applied at 10 degrees-20 degrees away from the easy-axis, the same is observed in CoFeB(12.5nm) film when the magnetic field is 45 degrees-55 degrees away from easy-axis. Unlike the previous reports of multi-jump switching in epitaxial films, their observance in the present case of amorphous CoFeB is remarkable. This multi-jump switching is found to disappear when the films are crystallized by annealing at 420 degrees C. The deposition geometry and the energy of the sputtered species appear to intrinsically induce a kind of bond orientation anisotropy in the films, which leads to the UMA in the as-grown amorphous CoFeB films. Exploitation of such multi-jump switching in amorphous CoFeB thin films could be of technological significance because of their applications in spintronic devices. (C) 2013 AIP Publishing LLC.