Incommensurate spiral magnetic order on anisotropic triangular lattice: Dynamical mean-field study in a spin-rotating frame

We study the ground-state magnetism of the half-filled Hubbard model on the anisotropic triangular lattice, where two out of three bonds have hopping t and the third one has t′ in a unit triangle. Working in a spin-rotating frame and using the density matrix renormalization group method as an impurity solver, we provide a proper description of incommensurate magnetizations at zero temperature in the framework of the dynamical mean-field theory (DMFT). It is shown that the incommensurate spiral magnetic order for t′/t0.7 survives the dynamical fluctuations of itinerant electrons in the Hubbard interaction range from the strong-coupling (localized-spin) limit down to the insulator-to-metal transition. We also find that when the anisotropy parameter t′/t increases from the Néel-to-spiral transition, the magnitude of the magnetic moment exhibits a maximum at the isotropic triangular lattice point t′/t=1 and then rapidly decreases in the range of larger t′/t. This work gives a solid foundation for further extension of the study including nonlocal correlation effects neglected at the standard DMFT level.