Authors: Elena Gorelik and Nils Blümer
One of the most anticipated milestones in the field of ultracold quantum gases is the expected realization of the antiferromagnetic (AF) Néel phase. Despite of high interest and extensive experimental and theoretical efforts no AF signatures have been seen so far. While experimental efforts are mostly concentrated on the achievement of low enough temperatures, another aspect of crucial importance for the successful detection of Néel phases is the proper choice of observables.
We present Hirsch-Fye quantum Monte Carlo (QMC) based real-space DMFT studies of temperature effects on the ordering phenomena, employing a new massively parallel implementation scaling to some 10000 atoms on a cubic optical lattice without significant approximations beyond DMFT (or NRG artifacts). We demonstrate that the onset of AF correlations at low T is signaled, for interactions U greater than about 10t, by a strongly enhanced double occupancy. Our detailed quantitative predictions should provide essential guidance to experimentalists; in contrast, LDA appears insufficient. Entropy estimates are derived from thermodynamic relations.
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