相关论文: Spin diffusion and the anisotropic spin-1/2 Heisen…
Finite-temperature local spin dynamics within the random spin-1/2 antiferromagnetic Heisenberg chain is studied numerically. The aim is to explain measured NMR spin-lattice relaxation times in BaCu_{2}(Si_{0.5}Ge_{0.5})_{2}O_{7}, which is…
We consider the isotropic $S=1$ Heisenberg chain with a finite Haldane gap $\Delta$ and use state-of-the-art numerical techniques to investigate its dynamical properties at finite temperature, focusing on the nuclear spin-lattice relaxation…
Low-frequency spin dynamics in the S=1/2 antiferromagnetic spin-chain compound \alpha-VO(PO_3)_2 has been studied by means of 31P NMR. The nuclear spin-lattice relaxation rate 1/T_1 at the P site exhibits H^{-1/2} dependence on the applied…
We present a careful analysis of the temperature dependence of the nuclear spin-lattice relaxation rate $1/T_1$ in gapped quasi-1D Heisenberg antiferromagnets. It is found that in order to estimate the value of the gap correctly from…
We make a modified spin-wave description of the nuclear spin relaxation in Heisenberg alternating-spin chains with antiferromagnetic exchange coupling. In contrast with the conventional one-dimensional antiferromagnetic spin-wave theory,…
In response to recent proton spin relaxation-time measurements on NiCu(pba)(H$_2$O)$_3$$\cdot$2H$_2$O with ${pba}=1,3{-propylenebis(oxamato)}$, which is an excellent one-dimensional ferrimagnetic Heisenberg model system of spin-$(1,{1/2})$,…
The spin-lattice relaxation rate $1/T_1$ and the spin echo decay rate $1/T_{2G}$ for the spin-$1\over 2$ antiferromagnetic Heisenberg chain are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are…
We study the nuclear spin-lattice relaxation rate $1/T_1$ in the two-leg antiferromagnetic spin-1/2 Heisenberg ladder. More specifically, we consider the contribution to $1/T_1$ from the processes with momentum transfer $(\pi,\pi)$. In the…
We investigate spin diffusion in geometrically frustrated Heisenberg antiferromagnets. It is found that the diffusion constant gradually increases from its high temperature limit as the temperature approaches the peak temperature of the…
A theoretical interpretation is given to recent proton spin relaxation-time (T_1) measurements on NiCu(C_7H_6N_2O_6)(H_2O)_3$\cdot$2H_2O, which is an ideal one-dimensional ferrimagnetic Heisenberg model system of alternating spins 1 and…
We use numerical techniques to study dynamical properties at finite temperature ($T$) of the Heisenberg spin chain with random exchange couplings, which realizes the random singlet (RS) fixed point in the low-energy limit. Specifically, we…
Combining high-temperature expansions with the recursion method and quantum Monte Carlo simulations with the maximum entropy method, we study the dynamics of the spin-1/2 Heisenberg chain at temperatures above and below the coupling J. By…
We present a series expansion study of spin-S square-lattice Heisenberg antiferromagnets. The numerical data are in excellent agreement with recent neutron scattering measurements. Our key result is that the correlation length for S>1/2…
We study the finite temperature, low energy, long wave-length spectrum of the dynamic structure factor of the spin-$1/2$ antiferromagnetic Heisenberg chain in the presence of exchange anisotropy and external magnetic fields. Using…
The relaxation function theory of doped two-dimensional $S=1/2$ Heisenberg antiferromagnetic (AF) system in the paramagnetic state is presented taking into account the hole subsystem as well as both the electron and AF correlations. The…
The spin-diffusion constant of the 2D $t-J$ model is calculated for the first time using an analytical approach at high temperatures and a recently-developed numerical method based on the Lanczos technique combined with random sampling in…
We report a neutron scattering study of the instantaneous spin correlations in the two-dimensional spin S=5/2 square-lattice Heisenberg antiferromagnet Rb_2MnF_4. The measured correlation lengths are quantitatively described, with no…
The dynamics of spin at finite temperature in the spin-1/2 Heisenberg chain was found to be superdiffusive in numerous recent numerical and experimental studies. Theoretical approaches to this problem have emphasized the role of nonabelian…
We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic t-J Heisenberg model on the honeycomb lattice. Employing a generalized mean-field approximation for arbitrary…
We study the spin diffusion and spin conductivity in the square lattice Hubbard model by using the finite-temperature Lanczos method. We show that the spin diffusion behaves differently from the charge diffusion and has a nonmonotonic $T$…