The development of motility mechanisms controllable on the sub-micron length scale is crucial for both nanorobotics and shapeable magnetoelectronics. We showcase that the nanoscale shape deformation of a flexible magnet can be controlled by its magnetic attributes. Namely, we consider a problem of coupling the geometrical and magnetic degrees of freedom of an elastic loop-shaped nanowire. The minimum energy states of the system essentially depend on its geometric, magnetic, and elastic parameters. Depending on the parameters, one can distinguish two different states: a sufficiently small magnetic ring is magnetized almost uniformly, forming an `onion state’ with two magnetic domain walls. An opposite case of large, rigid magnetic rings is characterized by a flux free vortex state. These findings open new avenues of investigation with deformable, multiply connected magnetic rings for applications in multifunctional nanorobotics.
**Publication:**

Yuri Gaididei, Kostiantyn V. Yershov, Denis D. Sheka, Volodymyr P. Kravchuk, Avadh Saxena,

*Magnetization-induced shape transformations in flexible ferromagnetic rings*,

Phys. Rev. B **99**, 014404 (2019),

doi: 10.1103/PhysRevB.99.014404 (pdf)

(supplementary materials).

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