To ensure a sufficiently large switching barrier in the proposed spinristor, we arrived at two model EMFs, Ti@C70-D5h(1) and Zr@C70-D5h(1), that show field-free barriers for relocation of their metal of 16.6 and 23.0 kcal.mol -1 , respectively. We utilized the fact that group 4 to 6 elements are known to form strong polar-covalent bonds to carbon atoms and that C70-D5h(1) fullerene has an elliptical non-isotropic shape with distinct binding sites for the selected metal atoms. The proposed systems should combine reasonable switching barriers with spin-polarized electronic structures because of the enclosed metal, which brings in the spin-filtering function. However, in the case of Zr@C70, our computations predict that the external electric potential does not decrease the switching barrier to a level to be applicable in a real device. The Zr@C70 can still function as a spin filter. Therefore, we keep the discussion in the main text limited to the Ti@C70-D5h(1) system while all data regarding the Zr@C70 are collected in SI.