Kinetic magnetism and stripe order in the antiferromagnetic bosonic t-J model

Unraveling the interplay between spin and charge degrees-of-freedom in doped quantum magnets is a central challenge in strongly correlated many-body physics, particularly regarding the role of particle statistics in the formation of striped and superconducting phases. Quantum simulation platforms, e.g., ultracold atoms trapped in optical lattices or tweezer arrays, provide a powerful tool to investigate such phenomena in microscopic detail. Here, we present our results disentangling the role of particle statistics from the intrinsic physics of strong correlations in the antiferromagnetic (AFM) bosonic t-J model. Using large-scale density matrix renormalization group (DMRG) calculations, we map out the T=0 phase diagram on the 2D square lattice [1]. At low doping, we find evidence of partially-filled stripe structures associated with incommensurate AFM correlations, reminiscent of those observed in high-T_c cuprates. As doping increases, a transition occurs to a partially-polarized ferromagnetic (FM) phase, driven by formation of Nagaoka polarons–i.e., mobile holes bound to localized FM regions–which may be directly detected via site-resolved snapshots of the many-body wavefunction. At high doping or large t/J, these polarons overlap, and the system evolves into a full-polarized ferromagnet. Our findings shed new light on the role of particle statistics in strongly correlated many-body systems, revealing connections to stripe formation and the physics of kinetic (i.e., Nagaoka-type) ferromagnetism. I will also discuss experimental realizations of this model in bosonic quantum gas microscopes, leveraging negative absolute temperature states to engineer local AFM superexchange interactions between bosons [2], thereby paving the way for future studies of doped bosonic quantum magnets.

[1] T. J. Harris, U. Schollwöck, A. Bohrdt and F. Grusdt, arXiv:2410.00904 (2024).

[2] A. Bohrdt et al., arXiv:2410.19500 (2024).