Fig. S2. The magnetization process of the magnetic beam component. The pre-magnetized beam in (A) was rolled in a cylindrical jig, and then magnetized by a strong, uniform magnetic field of  in (B). The free ends of the beam were illustrated at the exaggerated gap in (B). (C) Once the magnetic beam recovered back to its original shape, it would possess the optimal harmonic magnetization profile that had a phase shift angle ( ) of .