Phase separation in models for correlated electrons

Superconductivity near phase separation in models of correlated electrons.

Numerical and analytical studies of several models of correlated electrons are discussed. Based on exact diagonalization and variational Monte Carlo techniques , we have found strong indications that the two dimensional t − J model supercon-ducts near phase separation in the regime of quarter-filling density, in agreement with previous results reported by Dagotto and Riera (Phys. Rev. Letters 7...

Quantum phase transitions of correlated electrons in two dimensions

We review the theories of a few quantum phase transitions in two-dimensional correlated electron systems and discuss their application to the cuprate high temperature superconductors. The coupled-ladder antiferromagnet displays a transition between the Néel state and a spin gap paramagnet with a sharp S = 1 exciton: we develop a careful argument which eventually establishes that this transition...

Staggered flux phase in a model of strongly correlated electrons.

We present numerical evidence for the existence of a staggered flux (SF) phase in the half-filled two-leg t-U-V-J ladder, with true long-range order in the countercirculating currents. The density-matrix renormalization-group finite-size scaling approach, generalized to describe complex-valued Hamil-tonians and wave functions, is employed. The SF phase exhibits robust currents at intermediate v...

Organic phase-transition transistor with strongly correlated electrons

Blind Separation of Jointly Stationary Correlated Sources

The separation of unobserved sources from mixed observed data is a fundamental signal processing problem. Most of the proposed techniques for solving this problem rely on independence or at least uncorrelation assumption for source signals. This paper introduces a technique for cases that source signals are correlated with each other. The method uses Wold decomposition principle for extracting ...