Modulation of magnetic anisotropy by bending in Ni and Ni₇₈Fe₂₂ thin films on polycarbonate organic substrates

We investigate surface morphologies and magnetic/electrical properties, in which the bending dependence of the anisotropic magnetoresistance (AMR) effect and magnetic anisotropic field are focused on, of Ni and Ni₇₈Fe₂₂ thin films on polycarbonate (PC) substrates. The magnetic easy axis of the Ni (Ni₇₈Fe₂₂) thin films is rotated by bending the films in a convex (concave) shape. Bending the Ni/PC films in a concave shape enhances the magnetoresistance (MR) ratio by a factor of 1.4 and increases the magnetic anisotropic field from 13 to 240 mT. Whereas, bending Ni₇₈Fe₂₂/PC films in a convex shape enhances the MR ratio by a factor of 1.9 and increases the magnetic anisotropic field from 3.4 to 31 mT. These results are attributed to the inverse magnetostrictive effect. The results also reveal that the bending direction, which enhances the AMR effect, is determined by the sign of the magnetostriction constant. Bending-induced magnetic tuning can be a powerful tool for developing high-performance magnetic materials and spintronic devices.