ar X iv : c on d - m at / 9 60 10 27 v 1 9 J an 1 99 6 A possible phase diagram of a t - J ladder model

ar X iv : c on d - m at / 9 60 81 38 v 1 2 8 A ug 1 99 6 Ground State Phases of the Doped 4 - Leg t - J Ladder Steven

Using density matrix renormalization group techniques, we have studied the ground state of the 4-leg t-J ladder doped near half-filling. Depending upon J/t and the hole doping x, three types of ground state phases are found: (1) a phase containing d x 2 −y 2 pairs; (2) a striped CDW domain-wall phase, and (3) a phase separated regime. A CDW domain-wall consists of fluctuating hole pairs and thi...

ar X iv : c on d - m at / 9 60 72 19 v 1 3 0 Ju l 1 99 6 The phase diagram of high - T c ’ s : Influence of anisotropy and disorder

We propose a phase diagram for the vortex structure of high temperature superconductors which incorporates the effects of anisotropy and disorder. It is based on numerical simulations using the three-dimensional Josephson junction array model. We support the results with an estimation of the internal energy and configurational entropy of the system. Our results give a unified picture of the beh...

ar X iv : c on d - m at / 9 60 31 90 v 1 2 9 M ar 1 99 6 The Four - Dimensional XY Spin Glass

ar X iv : c on d - m at / 9 60 40 14 v 1 2 A pr 1 99 6 Quantum Hall Effect and Chaotic Motion in Phase Space

We discuss the relation between the Quantum Hall behaviour of charged carriers and their chaotic motion in phase space. It is shown that the quantum Hall diagram is comparable with the stepped diagram in phase space of a chaotic motion.

ar X iv : c on d - m at / 9 60 20 54 v 1 9 F eb 1 99 6 Phase Separation in the Hubbard Model

Making use of symmetry properties and known exact results for the Hubbard Model on bipartite lattice, we show that (1) there is no phase separation for repulsive coupling at low dopings, (2) phase separation and superconductivity co-exist in the ground states for attractive coupling in a range of filling fractions.