Marcin Raczkowski

Unidirectional d -wave superconducting domains in the two-dimensional t − J model

Using the t-J model at x=1/8 doping, we investigate the emergence of spontaneous modulations in the d-wave superconducting resonating valence bond phase which may be connected to the recently observed pattern of unidirectional domains found in scanning tunneling microscopy studies of high-T_c superconductors [Y. Kohsaka et al., Science 315, 1380 (2007)]. Half-filled charge domains separated by four lattice spacings are found to form along one of the crystal axis leading to modulated superconductivity with {\it out-of-phase} d-wave order parameters in neighboring domains. Both renormalized mean-field theory and variational Monte Carlo calculations yield that the energies of modulated and uniform phases are very close to each other.

Stability of RVB hole stripes in high-temperature superconductors

Indications of density-wave states in underdoped cuprates, coming from recent scanning tunneling microscopy and Hall-resistance measurements, have raised concerns whether stripes could be stabilized in the superconducting phase of cuprate materials, even in the absence of antiferromagnetism. Here, we investigate this issue using state-of-the-art quantum Monte Carlo calculations of a

Microscopic origin of diagonal stripe phases in doped nickelates

t\text{\ensuremath{-}}J

Spin rotationally symmetric domain flux phases in underdoped cuprate superconductors

model. In particular we consider the stability of unidirectional hole domains in a modulated superconducting background by taking into account the effect of tetragonal-lattice distortions, next-nearest-neighbor hopping, and long-range Coulomb repulsion.

Mott Quantum Criticality in the Anisotropic 2D Hubbard Model.

We investigate the electron density distribution and the stability of stripe phases in a realistic two-band model with hopping elements between

Spinon confinement: Dynamics of weakly coupled Hubbard chains

{e}_{g}

Dimensional-crossover-driven Mott transition in the frustrated Hubbard model.

orbitals at Ni sites on the square lattice, and compare these results with those obtained for the doubly degenerate Hubbard model with two equivalent orbitals and diagonal hopping. For both models we determine the stability regions of filled and half-filled stripe phases for increasing hole doping

Supersolid phases of a doped valence-bond quantum antiferromagnet: Evidence for a coexisting superconducting order parameter

x=2\ensuremath{-}n

Magnetic and orbital correlations in a two-site molecule

in the range of

Spin stiffness and quantum fluctuations in C-type and A-type antiferromagnets

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