= Solution
A point <magnetic dipole> $\boldsymbol\mu$ produces
$$
\mathbf B(\mathbf r)=\frac{\mu_0}{4\pi r^3}
\left[3(\boldsymbol\mu\cdot\hat r)\hat r-\boldsymbol\mu\right].
$$
For $|\mu|\sim\mu_B$ and neighbour separation $r\sim0.2\,\mathrm{nm}$, its characteristic magnitude is
$$
\boxed{B_{\rm dip}\sim\frac{\mu_0\mu_B}{4\pi r^3}\simeq0.116\,\mathrm T.}
$$
The axial field is twice this scale; the exact orientation and crystal geometry are unspecified. The corresponding pair <magnetic dipole interaction> has <energy> scale $U_{\rm dip}\sim\mu_BB_{\rm dip}\simeq1.08\times10^{-24}\,\mathrm J$, giving
$$
\boxed{T_{\rm dip}\sim\frac{U_{\rm dip}}{k_B}\simeq0.078\,\mathrm K\sim0.1\,\mathrm K.}
$$
An axial orientation changes this to about $0.16\,\mathrm K$. A real ordering <temperature> depends on a lattice sum, symmetry and fluctuations, so this is a nearest-neighbour <energy> estimate, not a complete ordering calculation. It establishes that ordinary dipolar coupling is far too weak to explain a thousand-kelvin ferromagnetic transition.
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