相关论文: Model for spin coupling disorder effects on the su…
The low-temperature behavior of the static magnetic susceptibility $\chi(T)$ of exchange-disordered antiferromagnetic spin chains is investigated. It is shown that for a relatively small and even number of spins in the chain, two exchange…
We study thermodynamic properties of the one-dimensional Heisenberg ferrimagnet with antiferromagnetically exchange-coupled two kinds of spins 1 and 1/2. The specific heat and the magnetic susceptibility are calculated employing a modified…
The magnetization behavior of q-periodic antiferromagnetic spin 1/2 Heisenberg chains under uniform magnetic fields is investigated in a background of disorder exchange distributions. By means of both real space decimation procedures and…
we investigate the thermodynamic properties of weakly anisotropic disordered magnetic chains where the nearest-neighbor Heisenberg exchange coupling is the dominant spin-spin interaction. In addition to the exchange interaction, there is…
The thermodynamics of finite open antiferromagnetic XXZ chains is studied using field theory, Bethe Ansatz and quantum Monte Carlo methods. For the susceptibility a parameter-free result as a function of the number of sites L and…
We present a study of the spin-1/2 Heisenberg chain with alternating ferro- and antiferromagnetic exchange, focusing on the role of the exchange couplings to cover both, dimer and Haldane limit. Employing a complementary combination of…
The thermodynamic properties of a spin S=1/2 tetrameric Heisenberg antiferromagnetic chain with alternating interactions AF1-AF2-AF1-F (AF and F denote the antiferromagnetic and ferromagnetic couplings, respectively) are studied by means of…
We investigate the low-temperature thermodynamics of the spin-1/2 Heisenberg chain with open ends. On the basis of boundary conformal field theory arguments and numerical density matrix renormalization group calculations, it is established…
Thermodynamic properties of a tetrameric bond-alternating Heisenberg spin chain with ferromagnetic-ferromagnetic-antiferromagnetic-antiferromagnetic exchange interactions are studied using the transfer-matrix renormalization group and…
The ordering of weakly coupled random antiferromagnetic $S=1/2$ chains, as relevant for recent experimentally investigated spin chain materials, is considered theoretically. The one-dimensional isotropic Heisenberg model with random…
Using the quantum Monte Carlo Loop algorithm, we calculate the temperature dependence of the uniform susceptibility, the specific heat, the correlation length, the generalized staggered susceptibility and magnetization of a spin-1/2 chain…
We consider the spin-1/2 XY chain in a transverse field with regularly varying exchange interactions and on-site fields. In two limiting cases of the isotropic XX and extremely anisotropic (Ising) exchange interaction the thermodynamic…
The magnetic and thermodynamic properties of a new ferrimagnetic decorated spin-(1/2,1) Heisenberg chain with spin-1 pendant spins are investigated for three cases: (A) J1,J2>0; (B) J1>0, J2<0; and (C) J1<0, J2>0, where J1 and J2 are the…
We present results for the dynamic structure factor of the S=1/2 bond alternating Heisenberg chain over a large range of frequencies and temperatures. Data are obtained from a numerical evaluation of thermal averages based on the…
We study disordered antiferromagnetic spin-1/2 chains with nearest- and further-neighbor interactions using the real-space renormalization-group method. We find that the system supports two different phases, depending on the ratio of the…
We investigate spin correlations in one-dimensional $SU(2)$-invariant Heisenberg chains with exchange disorder for spin lengths $S=1/2$ and $S=1$. In the weak-disorder regime, the eigenmodes of the spin-spin correlation matrix are…
We study an exotic Kondo effect in a system consisting of two one-dimensional XX Heisenberg ferromagnetic spin $1/2$ chains (denoted by $\alpha = u, d$ for up and down chains) coupled to a quantum dot consisting of two localized spin $1/2$…
We study a model of two weakly coupled isotropic spin-1/2 Heisenberg chains with an antiferromagnetic coupling along the chains. It is shown that the system always has a spectral gap. For the case of identical chains the model in the…
The one-dimensional XXZ model is studied in the presence of disorder in the Heisenberg Exchange Integral. Recent predictions obtained from renormalization group calculations are investigated numerically using a Lanczos algorithm on chains…
Using the Continuous Time Quantum Monte Carlo Loop algorithm, we calculate the temperature dependence of the uniform susceptibility, and the specific heat of a spin-1/2 chain with random antiferromagnetic and ferromagnetic couplings, down…