Fig. 1: Compositional phase diagram.

Schematic phase diagram of the equilibrium and metastable SkLs on the temperature-composition plane for four (Co_0.5Zn_0.5)_20−xMn_x compounds. Phase boundaries are reproduced from Ref. ⁵⁴. The green area indicates the thermodynamically stable SkL pocket below the Curie temperature (blue circles and line). The regime of the metastable SkL phases with pale yellow shading, achieved via a field cooling process^37,38,54, is separated into four regimes: (1) the transition from the equilibrium SkL into a metastable SkL, preserving the hexagonal symmetry, indicated by green triangles; (2) the crossover from the metastable hexagonal to a metastable square SkL phase in Co₇Zn₇Mn₆, Co₈Zn₈Mn₄ and Co₉Zn₉Mn₂, indicated by red squares, (3) the transformation of the metastable hexagonal into a metastable rhombic SkL state in Co₁₀Zn₁₀, marked by a violet rhombus and (4) the onset of a spin-glass phase (SG) in Co₇Zn₇Mn₆ and Co₈Zn₈Mn₄, marked by light blue stars. Characteristic temperatures have only been determined for the four compounds and the lines connecting the symbols are to support an easy visualisation.