arXiv:1905.05838 · Physical review. B./Physical review. B
Magnetic phase diagram of the infinite- U Hubbard model with nearest- and next-nearest-neighbor hoppings
G. G. Blesio, M. G. Gonzalez, Franco T. Lisandrini
Abstract
We study the infinite-$U$ Hubbard model on ladders of two, four, and six legs with nearest- $(t)$ and next-nearest- $({t}^{\ensuremath{'}})$ neighbor hoppings by means of the density-matrix renormalization group algorithm. In particular, we analyze the stability of the Nagaoka state for several values of ${t}^{\ensuremath{'}}$ when we vary the electron density $\ensuremath{\rho}$ from half filling to the low-density limit. We build the two-dimensional phase diagram, where the fully spin polarized and paramagnetic states prevail. We find that the inclusion of a nonfrustrating next-nearest-neighbor hopping stabilizes the fully spin polarized phase up until $|{t}^{\ensuremath{'}}/t|=0.5$. Surprisingly, for this value of ${t}^{\ensuremath{'}}$, the ground state is fully spin polarized for almost any electron density $1\ensuremath{\gtrsim}\ensuremath{\rho}\ensuremath{\gtrsim}0$, connecting the Nagaoka state to itinerant ferromagnetism at low density. Also, we find that the previously found checkerboard insulator phase at ${t}^{\ensuremath{'}}=0$ and $\ensuremath{\rho}=0.75$ is unstable against ${t}^{\ensuremath{'}}$.