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**We determine antiferromagnetic (AF) signatures in the half-filled Hubbard model at strong coupling on a cubic lattice and in lower dimensions. Upon cooling, the transition from the charge-excitation regime to the AF Heisenberg regime is signaled by a universal minimum of the double occupancy at entropy s=S/(Nk _{B})=s^{*}~ln(2) per particle and a linear increase of the next-nearest-neighbor (NNN) spin correlation function for s**

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