1201.5576 (E. V. Gorelik et al.)

Universal probes for antiferromagnetic correlations and entropy in cold
fermions on optical lattices    [PDF]

E. V. Gorelik, D. Rost, T. Paiva, R. Scalettar, A. Klümper, N. Blümer

We determine antiferromagnetic (AF) signatures in the half-filled Hubbard
model at strong coupling for 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/(N k_B)=log(2) per particle and a linear increase of the next-nearest
neighbor (NNN) spin correlation function below. This crossover, driven by a
gain in kinetic exchange energy, appears as the essential AF physics relevant
for current cold-atom experiments. The detection of long-range AF order
requires measurements of spin correlations at or beyond NNN distances.

View original: http://arxiv.org/abs/1201.5576