Fluctuation effect on the stripe order in the two-dimensional Hubbard model

Abstract

The stripe order appears in several transition metal oxides, such as La2−xSrxNiO4 and La2−x−yNdySrxCuO4. Results of mean-field calculation show appropriate zero temperature stable phase and band structures, but do not predict finite temperature stable phases. Especially, the mean field calculation shows that the spin and charge stripe orders appear simultaneously from antiferromagnetic state as decreasing temperature, but the neutron scattering experiment shows that the charge ordering appears first from paramagnetic states then the spin ordering appears. We consider the effect of spin and charge fluctuations to the stripe order. For this purpose, we apply FLEX approximation with mean field approximation to the two-dimensional Hubbard model. We find that the charge ordered state becomes stable under the spin fluctuation.