We present resistivity, magnetization, and specific-heat measurements on flux-grown single crystals of NiBi 3 . We find typical behavior of a type-II superconductor, with, however, a sizable magnetic signal in the superconducting phase. There is a hysteretic magnetization characteristic of a ferromagnetic compound. By following the magnetization as a function of temperature, we find a drop at temperatures corresponding to the Curie temperature of ferromagnetic amorphous Ni. Thus, we assign the magnetism in NiBi 3 crystals to amorphous Ni impurities.

Modifying the shape and size of magnetoelectronics-based devices and soft robotics by controlling an external magnetic (or electric) field is a goal not fully achieved at the present moment. Nevertheless, the concept of shapeable magnetronics is a corner- stone in researches at the nanoscale size. This work consists of a theoretical contribu- tion to this area of knowledge. Here, we study the effects of the mechanical, elastic, and magnetic parameters in the curvature of a surface initially set in a disk geometric configuration. The disk is free to move inside a specific transformation ranging from a hyperbolic paraboloid (saddle) to a paraboloid. We also use examples to sustain a proposed conjecture interconnecting the type of magnetization configuration (Vortex or Anti-Vortex) lying on the surface and its curvature. Keywords: Magnetism. Paraboloid. Nanostructured materials.