Effects of inhomogeneity on the spectrum of the Mott-insulator state (7 pages)

Nikolay V. Prokof'ev, Carl J. Williams, Guido Pupillo

Andrey R. Kolovsky

Masanori Kohno

Kai Phillip Schmidt, Alexander Reischl

Vera Guarrera, L. Fallani, Jessica Lye +2 more

We report an analysis of the inhomogeneous broadening of the excitation spectrum of a three-dimensional (3D) Mott insulator (MI) due to the presence of weak disorder. We present a theoretical model predicting the modification in the spectrum and compare the results to the experimental data obtained for a system of ultracold 87 Rb atoms in a 3D optical lattice, where quasi-disorder is added by means of an auxiliary 1D optical lattice with non-commensurate wavelength. The model shows good agreement with the measured points, confirming a significant broadening of the MI spectrum resonances even for a very small height of the disordering potential.

志朗 酒井, Nayuta Takemori

We study the effect of carrier doping to the Mott insulator on the Penrose tiling, aiming at clarifying the interplay between quasiperiodicity and strong electron correlations. We numerically solve the Hubbard model on the Penrose-tiling structure within a real-space dynamical mean-field theory, which can deal with a spatial inhomogeneity as well as a singular self-energy necessary to describe the Mott insulator. We find that the strong correlation effect produces a charge distribution unreachable by a static mean-field approximation. In a small doping region, the spectrum shows a site-dependent gap just above the Fermi energy, which is generated by a singularly large self-energy emergent from the Mott physics and regarded as a real-space counterpart of the momentum-dependent pseudogap observed in a square-lattice Hubbard model.