Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet ${\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ with $x=0.3$ reveal a pronounced effect of the magnetic history and cooling rates on the magnetic phase diagram. The extracted phase diagrams are qualitatively different for zero and field cooling and reveal a metastable skyrmion lattice phase outside the $A$ phase for the latter case. These thermodynamically metastable skyrmion lattice correlations coexist with the conical phase and can be enhanced by increasing the cooling rate. They appear in a wide region of the phase diagram at temperatures below the $A$ phase but also at fields considerably smaller or higher than the fields required to stabilize the $A$ phase.

• Received 25 April 2016
• Revised 2 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.104406