Extended skyrmion lattice scattering and long-time memory in the chiral magnet Fe$_{1-x}$Co$_x$Si

TL;DR

This study uses neutron scattering to explore how magnetic history and cooling rates affect skyrmion phases in Fe$_{1-x}$Co$_x$Si, revealing metastable skyrmion states outside the conventional A-phase.

Contribution

It demonstrates the influence of magnetic history and cooling rates on the phase diagram and identifies metastable skyrmion lattice correlations outside the A-phase in doped chiral magnets.

Findings

Metastable skyrmion lattice correlations exist outside the A-phase.

Cooling rate enhances metastable skyrmion correlations.

Magnetic history significantly alters the phase diagram.

Abstract

Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet Fe$_{1-x}$Co$_x$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.