A.N. Kocharian, Kun Fang, G.W. Fernando, A. Balatsky
California State University. Los Angeles,
Keywords: Mott metal-insulator transition, phase separation, first and second order phase transitions
Summary:The modeled of many body physics and possible spontaneous phase separation instabilities in various two-dimensional square and honeycomb structures (generated by periodically repeated Betts lattices) provide an ideal playground for understanding of various competing phases and intrinsic cooperative effects in strongly correlated materials with honeycomb lattice geometries. The important difference between this approach and previously employed exact diagonalization, cluster dynamical approximation and quantum Monte Carlo is discussed. The results highlight also important aspects of the interplay of the spin-orbit coupling with magnetic field in graphene-like systems and unconventional superconductors induced by weak, moderate and strong electron interaction. However, a density variation with the chemical potential shows their distinct structural differences under doping away from half filling. For example, in equilibrium we found discontinuous transition and density anomaly in square lattices signaling phase separation instability into inhomogeneous state with hole rich (metallic) and hole poor (insulating) regions. In contrast, honeycomb lattice does not have density anomaly, but instead the density displays a smooth transition and describes a continuous evolution of homogenous (metallic) state. The implication of VCA results to HTSCs, layered graphene, topological insulators as well as comparison to other studies are discussed.