Soft magnetic nano-strings simultaneously grown and sculpted on Si micro-cantilevers

Si micro-cantilevers, MCTVS, were coated by off-normal deposition with Co soft magnetic films that had a nano-string surface morphology. This nano-structure generated an in-plane uniaxial magnetic, electrical and optical anisotropy in the films. The width of the nano-strings was controlled between 8 and 30 nm by selecting the off-normal deposition parameters. Two sets of coated MCTV were produced: ones with nano-strings parallel to the longitudinal symmetry axis of the MCTV and the other ones with the nano-strings perpendicular to this axis. The morphological anisotropy present in the Co film was also reflected in a mechanical anisotropy in the MCTVS. For MCTVS coated with longitudinal nano-strings, the frequency of the mechanical resonance decreased ∼1.5% with respect to the non-coated ones, while it decreased ∼3% for coated MCTVS with transversal nano-strings. This was explained in terms of the anisotropic elastic properties of the Co films. The extra changes of the frequency of the mechanical resonance produced by a magnetic field applied to the MCTV were discussed in considering also the magnetic anisotropy of the films.