Speaker
Description
We study variants of the two-leg t-J ladder at low fillings using matrix
product states (MPS) and analytical methods. While the groundstate phase
diagram for the usual t-J ladder with spatially isotropic couplings at
fillings $n>0.5$ has been studied in detail, relatively little is known
at low fillings. We address the phase diagram at low fillings and
investigate the influence of nearest-neighbor Coulomb interactions $V$
and asymmetries in the spin-exchange $J_z \neq J_x = J_y$ on the size and
nature of superconducting phases. For $V=0$ the superconducting phase is
enhanced, and we find a crossover within this phase from s-wave pairing
to d-wave pairing when increasing the filling. For Jz=0, the size of the
superconducting region is reduced. In this talk, I will present the
phase diagrams, discuss the physics, briefly introduce the methods used
to classify the different phases, and give an outlook towards 2D systems
and possible realizations in experiments.
