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arXiv · 1201.5576

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

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

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/(N k_B)=s*=ln(2) per particle and a linear increase of the next-nearest neighbor (NNN) spin correlation function for s<s*. This crossover, driven by a gain in kinetic exchange energy, appears as the essential AF physics relevant for current cold-atom experiments. The onset of long-range AF order (at low s on cubic lattices) is hardly visible in nearest-neighbor spin correlations versus s, but could be detected in spin correlations at or beyond NNN distances.

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E. V. Gorelik, D. Rost, T. Paiva, R. Scalettar, A. Klümper, N. Blümer. 2012-06-05. Universal probes for antiferromagnetic correlations and entropy in cold fermions on optical lattices. https://doi.org/10.1103/physreva.85.061602

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