Magnetic correlations in the two-dimensional repulsive Fermi-Hubbard model

The repulsive Fermi-Hubbard model on a square lattice has a rich phase diagram near half-filling (n = 1): at n = 1 the ground state is an antiferromagnetic insulator, at 0.6 < n less than or similar to 0.8 the ground state is a d(x2-y2)-wave superfluid (at least for moderately strong interactions, U less than or similar to 4), and the region 1 - n << 1 is likely subject to phase separation. Much less is known about the nature of strong magnetic fluctuations at finite temperature and how they change with the doping level. Recent experiments on ultracold atoms have now reached this interesting fluctuation regime. In this work we employ the skeleton diagrammatic method to quantify the characteristic temperature scale T-M (n) for the onset of magnetic fluctuations with a large correlation length.