A method is proposed for calculating the surface energy density ${\gamma }_B$ of ${180}^{\circ }$ Bloch domain walls in uniaxial ferromagnetic crystals over the entire range of magnetic ordering temperatures. This method enables the determination of ${\gamma }_B$ for an arbitrary number of anisotropy constants $K_i\left(T\right)$ in the expansion of the magnetocrystalline anisotropy (MCA) energy and for various types of MCA. The method is tested using the intermetallic compound ${\mathrm{Nd}}_2{\mathrm{Fe}}_{14}\mathrm{B}$, which undergoes a spin-reorientation transition (SRT) at $T_{\text{SRT}}=135$ K from a high-temperature easy-axis MCA type to a low-temperature easy-cone type. The energy of ${180}^{\circ }$ Bloch domain walls in ${\mathrm{Nd}}_2{\mathrm{Fe}}_{14}\mathrm{B}$ was calculated in the temperature range of 78–293 K, taking into account sixth-order MCA constants. It is shown that using standard MCA expansions truncated at fourth-order terms is insufficient for accurately evaluating ${\gamma }_B$ near the SRT or in temperature ranges where the MCA type deviates from the easy-axis configuration.

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• Magnetic anisotropy
• Magnetic domains
• Magnetism
• Ferromagnets
• Micromagnetic modeling