(color online) (a) Color lines: first-order reversal curves for single-layer Nd–Dy–Fe–Co–B. Color contour plots: M and H_r dependence of the FORC function distribution; (b) the main analysis data: color contour plots of the H_c and H_b dependence of FORC function distribution. (c) Color lines: first-order reversal curves for Nd–Dy–Fe–Co–B (100 nm)/Ta (2 nm)/Fe (10 nm) multilayer. Color contour plots: M and H_r dependence of the FORC function distribution; (d) the main analysis data for Nd–Dy–Fe–Co–B (100 nm)/Ta (2 nm)/Fe (10 nm) multilayer: color contour plots of the H_c and H_b dependence of FORC function distribution. The color scale represents the distribution of the values of ρ.^[31]