Novel Approach to Control Diameter of Self-Rolled Magnetic Microtubes by Anodizing Ti Layer

Stress engineering in multilayered thin-film patterns is the key to control the diameter of self-rolled magnetic structures. Arrays of magnetic microtubes were fabricated via a deterministic release of rectangular thin-film patterns of Ti(20 nm)/Ni(30 nm)/Au(2 nm) and Ti(20 nm)/GaFe(40 nm)/Au(15 nm) from a sacrificial underlayer of Cu. It is demonstrated that the expansion of the anodized Ti layer leads to a reduction of the diameter of the tubes by almost 50%. The changes of shape of the magnetic patterns from flat to tubular and further reduction of the tube diameter due to anodizing were accompanied by changes of their magnetic characteristics.