  Magnetic materials can host skyrmions, which are topologically non-trivial
spin textures. In chiral magnets with cubic lattice symmetry, all
previously-observed skyrmion phases require thermal fluctuations to become
thermodynamically stable in bulk materials, and therefore exist only at
relatively high temperature, close to the helimagnetic transition temperature.
Other stabilization mechanisms require a lowering of the cubic crystal
symmetry. Here, we report the identification of a second skyrmion phase in
Cu$_{2}$OSeO$_{3}$ at low temperature and in the presence of an applied
magnetic field. The new skyrmion phase is thermodynamically disconnected from
the well-known, nearly-isotropic, high-temperature phase, and exists, in
contrast, when the external magnetic field is oriented along the
$\langle100\rangle$ crystal axis only. Theoretical modelling provides evidence
that the stabilization mechanism is given by well-known cubic anisotropy terms,
and accounts for an additional observation of metastable helices tilted away
from the applied field. The identification of two distinct skyrmion phases in
the same material and the generic character of the underlying mechanism suggest
a new avenue for the discovery, design, and manipulation of topological spin
textures.
