  Magnetometry and magnetoresistance measurements in MnSi thin films and
rigorous analytical solutions of the micromagnetic equations show that the
field-induced unwinding of confined helicoids occurs via discrete steps. A
comparison between the magnetometry data and theoretical results shows that
finite size effects confine the wavelength and lead to a quantization of the
number of turns in the helicoid. We demonstrate a prototypical spintronic
device where the magnetic field can push or pull individual turns into a
magnetic spring that can be read by electrical means.
