Enhanced magnetic coercivity and maximum energy product in double-perovskite Y$_{\mathrm{2}}$CoMnO$_{\mathrm{6}}$ single crystals

We have investigated the influence of different annealing conditions on the magnetic properties on the single crystals of double-perovskite Y$_{\mathrm{2}}$CoMnO$_{\mathrm{6}}$. The ferromagnetic moment along the c-axis with the large magnetic coercivity and high squareness ratio was observed. Particularly, in the quenched specimen, the magnetic functionality has been greatly improved compared to that of the as-grown crystal. The magnetic coercivity and maximum energy product have been increased by $\sim $120{\%} and $\sim $50{\%}, respectively, by comprising substantial disorders and defects. Our result renders an efficient route to improve the magnetic functionality in mixed-valent magnets.