Fig. 1: MixD Fermi–Hubbard systems.
From: Formation of individual stripes in a mixed-dimensional cold-atom Fermi–Hubbard system
a, Illustration of the isotropic 2d Fermi–Hubbard model. Holes delocalize within small regions and disturb their respective spin background, forming magnetic polarons. The overall hole density is uniform and holes repel each other owing to their fermionic statistics at experimentally accessible temperatures of kBT ≈ J. There are no ___domain walls in the spin order. b, By raising the potential on every other lattice site along y by Δ, we suppress tunnelling along this direction, thus removing the Pauli repulsion between holes, while preserving the superexchange coupling Jy. At low temperatures, the holes form collective structures, which also result in a ___domain wall in the AFM correlations of the system, indicated by the AFM parity change across the stripe. c, A single raw experimental shot of spin-up (red) and spin-down (blue) atoms and doubly occupied sites (purple), as well as its reconstructed spin and charge distribution with the main system being inside the black circle, surrounded by a low-density reservoir (see Supplementary Information). The green box indicates a stripe-like structure.
