  The recent years have witnessed an emergence of the field of all-spin-based
devices without any flow of charge. An ultimate goal of this scientific
direction is the realization of full spectrum of spin-based networks like in
modern electronics. The concepts of energy storing elements, indispensable for
those networks, are so far lacking. Analyzing analytically the size dependent
properties of magnetic chains that are coupled via either exchange or
long-range dipolar or Ruderman-Kittel-Kasuya-Yosida interactions, we discover a
particularly simple law: magnetic configurations corresponding to helices with
integer number of twists, that are commensurate with the chain's length, are
energetically stable. This finding, supported by simulations and an
experimentally benchmarked model, agrees with the study [J. Appl. Phys.
\textbf{111}, 07E116 (2012)] showing that boundaries can topologically
stabilize structures that are not stable otherwise. On that basis an energy
storing element is proposed.
