The temperature-dependent intrinsic magnetic properties of ${\mathrm{SmCo}}_5$ and its Fe- or Cu-doped compounds are systematically investigated via atomistic spin simulations. For pristine ${\mathrm{SmCo}}_5$, Curie temperature $T_{\text{C}}$ and effective anisotropy constant $K_1^{\text{eff}}$ at 0 K are calculated as 1000 K and $35\mathrm{MJ}\text{/}{\mathrm{m}}^3$, respectively, agreeing with experimental results. The domain-wall width ${\delta }_{\text{w}}$ and exchange stiffness $A_{\text{e}}$ at 0 K are determined as 3.31 nm and 39.3 pJ/m, respectively. As temperature increases, the domain wall broadens and both $K_1^{\text{eff}}\left(T\right)$ and $A_{\text{e}}\left(T\right)$ decrease, with a scaling law as $A_{\text{e}}\propto {[M_{\text{s}}\left(T\right)/M_{\text{s}}\left(0\right)]}^{1.86}$. For the metal-doped $\text{Sm}{\left({\text{Co}}_{1-x}{M}_x\right)}_5$ compounds ($M=\text{Fe},\text{Cu}$; $x=0.2,0.4$), magnetic Fe doping is found to increase $T_{\text{C}}$ through Fe-Co exchange, while nonmagnetic Cu doping decreases $T_{\text{C}}$. Both metal dopants reduce $K_1^{\text{eff}}$ by perturbing the Sm crystal field and Co spin-orbit coupling. Magnetic Fe doping is revealed to improve the thermal stability of the magnetic anisotropy of ${\mathrm{SmCo}}_5$, while nonmagnetic Cu doping weakens it. This work could advance the understanding of ${\mathrm{SmCo}}_5$ permanent magnets and the impact of transition-metal doping through a comprehensive quantification of their temperature-dependent magnetic properties.

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• Domain walls
• Magnetic anisotropy
• Magnetism