Ferromagnetic diagonal stripe states in the two-dimensional Hubbard model with $U\lesssim \mathrm{\infty }$

We have performed a variational Monte Carlo simulation to study the ground state of a two-dimensional Hubbard model on a square lattice in the strong coupling region. The energy gain of possible inhomogeneous electron states are computed as a function of $U$ when the hole density $\epsilon =1\mathrm{/}8$ and next nearest-neighbor hopping $t^{\mathrm{\prime }}\mathrm{/}t=-0.30$. The bond-centered ferromagnetic diagonal stripe state is stabilized in the strong coupling region ($U\mathrm{/}t\ge$16), which is due to the gain of both kinetic energy and on-site Coulomb interaction energy due to the holon moving over the ferromagnetic domain and the gain of kinetic-exchange-interaction energy at the antiferromagnetic domain wall.