Related papers: Bond-impurity induced bound states in disordered s…
We study effects of interladder coupling on critical magnetic properties of spin ladder systems doped with small concentrations of nonmagnetic impurities, using the scaling theory together with quantum Monte Carlo (QMC) calculations.…
We consider the effects of doping the S = 1/2 kagome lattice with static impurities. We demonstrate that impurities lower the number of low-lying singlet states, induce dimer-dimer correlations of considerable spatial extent, and do not…
The vortices of two-dimensional chiral $p$-wave superconductors are predicted to exhibit some exotic behaviors; one of their curious features is the existence of two types of vortices (each vortex has vorticity either parallel or…
Two electronic channels competing to screen a single impurity spin, as in the two-channel Kondo model, are expected to generate a ground state with nontrivial entanglement structure. We exploit a spin-chain representation of the two-channel…
Impurity-induced quasiparticle bound states on a pair-breaking surface of a d-wave superconductor are theoretically described, taking into account hybridization of impurity- and surface-induced Andreev states. Further a theory for effects…
We discuss the stability of ferromagnetic long-range order in three-dimensional classical XY ferromagnets upon substitution of a small subset of equally oriented bonds by impurity bonds, on which the ferromagnetic exchange J_perp > 0 is…
Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized by a gap in the spin-excitation spectrum, which can be modeled at low energies by that of Dirac fermions with a mass. In the presence of disorder these systems can…
Treating an exactly rung-dimerized spin ladder as a reference model we study perturbatively zero temperature quantum fluctuations in spin ladders with slightly destroyed rung-dimerization. Analytic expressions are obtained for the gas…
We investigate quantum impurity problems, where a local magnetic moment is coupled to the spin density of a bosonic environment, leading to bosonic versions of the standard Kondo and Anderson impurity models. In a physical situation, these…
In this paper, we review the recent activity of our group on the study of disorder effects on systems displaying phase coherence. These studies have focused on both the electronic transport through mesoscopic metallic spin glasses, and cold…
The effect of a ring exchange on doped two-leg ladders is investigated combining exact diagonalization (ED) and density matrix renormalization group (DMRG) computations. We focus on the nature and weights of the low energy magnetic…
We analyse a model of a one-dimensional electron gas interacting with an antiferromagnetic Heisenberg spin-1/2 chain via the spin exchange interactions. Using a solution at a special limit, we characterize the gapless modes of the spin gap…
The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-spin correlation…
We investigate numerically the problem of few (one, two) noninteracting spin$-1/2$ fermions in a shallow harmonic trap coupled via contact repulsive interactions to a uniform one-dimensional bath of lattice bosons, described by the…
An inelastic neutron scattering study was performed on a Zn-substituted spin-1/2 Heisenberg 2-leg ladder compound Sr(Cu1-xZnx)2O3 (x < 0.04) to investigate nonmagnetic impurity effects on the quantum spin system with a large spin gap of…
An Anderson impurity in a Hubbard model on chains with finite length is studied using the density-matrix renormalization group (DMRG) technique. In the first place, we analyzed how the reduction of electron density from half-filling to…
The bulk properties and impurity effect in the one-dimensional S=1/2 Heisenberg model with dimerization and next-nearest-neighbor exchange are studied by the density matrix renormalization group (DMRG) and exact diagonalization methods.…
In this paper, we have systematically studied the single hole problem in two-leg Hubbard and $t$-$J$ ladders by large-scale density-matrix renormalization group calculations. We found that the doped hole in both models behaves similarly…
It has been recently suggested that when an Anderson impurity is immersed in the bulk of a topological insulator, a Kondo resonant peak will appear simultaneously with an in-gap bound-state when the band-dispersion has an…
The effect of antiferromagnetic interchain coupling in alternating spin (1,1/2) chains is studied by mean of a spin wave theory and density matrix renormalization group (DMRG). In particular, two limiting cases are investigated, the two-leg…