We implement the rotationally-invariant formulation of the two-dimensional Hubbard model, with nearest-neighbors hopping $t$, which allows for the analytical study of the system in the low-energy...
The antiferromagnetic phase of two-dimensional (2D) and three-dimensional (3D) Hubbard model with nearest neighbors hopping is studied on a bipartite cubic lattice by means of the quantum SU(2)xU(1)...
We discuss the local and nonlocal dissipation effects on the existence of the global phase coherence transitions in two dimensional Josephson-coupled junctions. The quantum phase transitions are also...
Novel quantum criticality due to emergent topological conservation law in high-$T_c$ cuprates (2006)
We argue that in strongly correlated electron system collective instanton excitations of the phase field (dual to the charge) arise with a great degree of stability, governed by gauge flux changes by...
Generic gauge fields in the Hubbard model: emergence of pairing interaction (2006)
The spin-rotationally invariant SU(2) approach to the Hubbard model is extended to accommodate the charge degrees of freedom. Both U(1) and SU(2) gauge transformation are useed to factorize the...
The concept of topological excitations and the related ground state degeneracy are employed to establish an effective theory of the superconducting state evolving from the Mott insulator for high-Tc...
Possible origin of 60-K plateau in the YBa2Cu3O(6+y) phase diagram (2006)
We study a model of YBa2Cu3O(6+y) to investigate the influence of oxygen ordering and doping imbalance on the critical temperature Tc(y) and to elucidate a possible origin of well-known feature of...
We study the quantum phase transitions in two-dimensional arrays of Josephson-couples junctions with short range Josephson couplings (given by the Josephson energy) and the charging energy. We map...
The quantum interference effects due to the Aharonov-Bohm-type phase factors are studied in the layered $t-t'-t_\perp-U-J$ strongly correlated system relevant for cuprates. Casting Coulomb...
We study a model of $n$-layer high-temperature cuprates of homologous series like HgBa_2Ca_(n-1)Cu_nO_(2+2n+\delta) to explain the dependence of the critical temperature Tc(n) on the number $n$ of...
We study a quantum Hamiltonian that models an two--dimensional array of Josephson junctions with short range Josephson couplings, (given by the Josephson energy E_J and charging energiey E_C due to...
SO(5) superconductor in a Zeeman magnetic field: Phase diagram and thermodynamic properties (2002)
In this paper we present calculations of the SO(5) quantum rotor theory of high-T$_{c}$ superconductivity in Zeeman magnetic field. We use the spherical approach for five-component quantum rotors in...
Thermodynamic properties of the SO(5) model of high-Tc superconductivity (2002)
In this paper we present calculations of thermodynamic functions within Zhang's SO(5) quantum rotor theory of high-Tc superconductivity. Using the spherical approach for the three-dimensional quantum...
Three-dimensional Josephson-junction arrays in the quantum regime (1999)
We study the quantum phase transition properties of a three-dimensional periodic array of Josephson junctions with charging energy that includes both the self and mutual junction capacitances. We use...