The effects of the lattice distortions along the rung on the bound states of two holes doped away from half-filling in terms of electrons have been studied in the two-leg-spin ladders. As the electron-lattice interaction increases, the binding energy of two holes with negative value increases. Two holes along the rung form bound states with the spin singlet. It turns out that the electron-lattice interaction along the rung plays an important role in the bound states of two holes in the two-leg-spin ladders.
We analyze the formation of multi-particle bound states in ladders with frustrated kinetic energy in two component bosonic and two component fermionic systems. We focus on the regime of light doping relative to insulating states at half-filling, spin polarization close to 100 percent, and strong repulsive interactions. A special feature of these systems is that the binding energy scales with single particle tunneling
t rather than exchange interactions, since effective attraction arises from alleviating kinetic frustration. For two component Fermi systems on a zigzag ladder we find a bound state between a hole and a flipped spin (magnon) with a binding energy that can be as large as
0.6t. We demonstrate that magnon-hole attraction leads to formation of clusters comprised of several holes and magnons and expound on antiferromagentic correlations for the transverse spin components inside the clusters. We identify several many-body states that result from self-organization of multi-particle bound states, including a Luttinger liquid of hole-magnon pairs and a density wave state of two hole - three magnon composites. We establish a symmetry between the spectra of Bose and Fermi systems and use it to establish the existence of antibound states in two component Bose mixtures with SU(2) symmetric repulsion on a zigzag ladder. We also consider Bose and Fermi systems on a square ladder with flux and demonstrate that both systems support bound states. We discuss experimental signatures of multi-particle bound states in both equilibrium and dynamical experiments. We point out intriguing connections between these systems and the quark bag model in QCD.
We analyze the formation of multiparticle bound states in ladders with frustrated kinetic energy in two-component bosonic and two-component fermionic systems. We focus on the regime of light doping relative to insulating states at half-filling, spin polarization close to 100%, and strong repulsive interactions. A special feature of these systems is that the binding energy scales with single-particle tunneling t rather than exchange interactions, since effective attraction arises from alleviating kinetic frustration. For two-component Fermi systems on a zigzag ladder we find a bound state between a hole and a flipped spin (magnon) with a binding energy that can be as large as 0.6t . We demonstrate that magnon-hole attraction leads to formation of clusters comprising several holes and magnons, and we expound on antiferromagentic correlations for the transverse spin components inside the clusters. We identify several many-body states that result from self-organization of multiparticle bound states, including a Luttinger liquid of hole-magnon pairs and a density wave state of two-hole–three-magnon composites. We establish a symmetry between the spectra of Bose and Fermi systems and use it to establish the existence of antibound states in two-component Bose mixtures with SU(2) symmetric repulsion on a zigzag ladder. We also consider Bose and Fermi systems on a square ladder with flux and demonstrate that both systems support bound states. We discuss experimental signatures of multiparticle bound states in both equilibrium and dynamical experiments. We point out intriguing connections between these systems and the quark bag model in QCD. Published by the American Physical Society 2024