Spatial inhomogeneity and strong correlation physics: a dynamical mean field study of a model Mott-insulator/band-insulator heterostructure

We use the dynamical mean field method to investigate electronic properties of heterostructures in which finite number of Mott-insulator layers are embedded in a spatially infinite band-insulator. The evolution of the correlation effects with the number of Mott insulating layers and with position in the heterostructure is determined, and the optical conductivity is computed. It is shown that the heterostructures are generally metallic, with moderately renormalized bands of quasiparticles appearing at the interface between the correlated and uncorrelated regions.Comment: 4 pages, 4 figure

Non-Collinear Magnetic Phases of a Triangular-Lattice Antiferromagnet and Doped CuFeO2_2

We obtain the non-collinear ground states of a triangular-lattice antiferromagnet with exchange interactions up to third nearest neighbors as a function of the single-ion anisotropy $D$. At a critical value of $D$, the collinear \uudd phase transforms into a complex non-collinear phase with odd-order harmonics of the fundamental ordering wavevector \vQ . The observed elastic peaks at 2\pi \vx -\vQ in both Al- and Ga- doped CuFeO$_2$ are explained by a "scalene" distortion of the triangular lattice produced by the repulsion of neighboring oxygen atoms.Comment: 4 pages 3 figures, accepted for publication by Phys. Rev. B Rapid communication

Microscopic Inhomogeneity and Superconducting Properties of a Two-dimensional Hubbard Model for High-TcT_c Cuprate

Recent scanning tunneling microscopy measurements on cuprate superconductors have revealed remarkable spatial inhomogeneities in the single-particle energy gap. Using cellular dynamical mean-field theory, we study the zero temperature superconducting properties of a single-band Hubbard model with a spatial modulation of the electron density. We find that the inhomogeneity in the electronic structure results in a substantial spatial variation in the superconducting order parameter and single-particle energy gap, reminiscent of the experimental results. In particular, we find that the order parameter and gap amplitudes in the hole-rich regions are significantly enhanced over the corresponding quantities in a uniform system, if the hole-rich regions are embedded in regions with smaller hole density.Comment: 6 pages, 4 figures, and 2 table