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A point magnetic dipole $\mathbf{\mu }$ producesFor $|\mu |\sim {\mu }_B$ and neighbour separation $r\sim 0.2\mathrm{nm}$, its characteristic magnitude isThe axial field is twice this scale; the exact orientation and crystal geometry are unspecified. The corresponding pair magnetic dipole interaction has energy scale $U_{\mathrm{dip}}\sim {\mu }_B{B}_{\mathrm{dip}}\simeq 1.08\times 10^{-24}\mathrm{J}$, givingAn 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.

At greater concentration, the mean separation falls and the independent-moment approximation can fail. The magnetic dipole interaction has characteristic scalewith sign and angular dependence set by moment orientation. Correlated clusters, chains or frustrated arrangements change local fields and relaxation barriers.

A plausible example is a progressively less reversible loop with larger remanence/magnetic coercivity when interactions slow collective relaxation; the figure illustrates that case. The trend is not universal: some arrangements reduce susceptibility or suppress remanence, and aggregation can introduce a different response from a uniform concentrated dispersion. Neither loop area nor magnetic coercivity must vary monotonically with concentration.

At the actual drive frequency, the dissipated energy per cycle per unit volume is proportional to ${\mu }_0\oint HdM$. Measure this dynamic loop rather than inferring dissipation from an unrelated slow sweep. Compare equal magnetic-material amounts, inspect dispersion state, and vary frequency to separate concentration-driven interactions from simple signal scaling. No biological efficacy is inferred.