Fig. 1: Self-assembly rolling approach to study strain-induced changes in magnetic properties.

Schematic illustration of self-assembly a-i roll-down and b-i roll-up approach for adjusting sign and size of curvature and strain in a functional layer on top of the polymeric platform (PP). a-ii, b-ii Magnified view of the rolled structures, indicating tensile (yellow arrows) and compressive (black arrows) strain in the magnetic layer and illustrating the corresponding azimuthal and axial domain states. a-iii, b-iii Optical image of rolled-down and rolled-up polymer structure with contacted Ni₇₈Fe₂₂ stripe (scale bar, 200 µm) and a-iv, b-iv corresponding Kerr microscopical image of the domain state. Scale bar, 15 µm. c Schematic set-up of simultaneous magneto-optical and AMR measurement of a strained magnetic stripe lying on the dome of the polymeric tube. d Magnetic hysteresis and e AMR hysteresis were measured simultaneously on the Permalloy (Ni₇₈Fe₂₂) stripe with field along the stripe’s long axis (x-axis) before and after rolling.