Related papers: Low-Temperature Spin-Wave Approximation for the He…
We use the rotation-invariant Green's function method (RGM) and the high-temperature expansion (HTE) to study the thermodynamic properties of the spin-$S$ Heisenberg ferromagnet on the pyrochlore lattice. We examine the excitation spectra…
Small spin systems at the interface between analytical studies and experimental application have been intensively studied in recent decades. The spin ring consisting of four spins with uniform antiferromagnetic Heisenberg interaction is an…
We study the low energy spectrum of the nearest neighbor Heisenberg model on a square lattice as a function of the total spin S. By quantum Monte Carlo simulation we compute this spectrum for the s=1/2, s=1 and s=3/2 Heisenberg models. We…
The current theoretical and experimental situation is reviewed for low-dimensional (layered and chain-like) insulating systems. Such systems possess a low magnetic transition temperature $T_M$ and pronounced short-range magnetic order above…
We present a general theory for the intermediate temperature (T) properties of Heisenberg antiferromagnets of spin-S ions on p-leg ladders, valid for 2Sp even or odd. Following an earlier proposal for 2Sp even (Damle and Sachdev,…
Low-temperature thermodynamic properties of the spin-1/2 Heisenberg ladder system with non-magnetic impurities are discussed using an effective Hamiltonian for the impurity-induced spins in the background of a spin liquid with a gap. It is…
We developed a framework for directly calculating the spin susceptibility of anisotropic itinerant ferromagnets in the full temperature range within the coherent potential approximation in the disordered local moment picture. As a test of…
Phase diagram, critical properties and thermodynamic functions of the two-dimensional field-free quantum-spin-1/2 XXZ model has been calculated globally using a numerical renormalization group theory. The nearest-neighbor spin-spin…
We investigate a frustrated Heisenberg spin-1/2 antiferromagnet on a fractal lattice of dimension d=ln3/ln2 (Sierpinski gasket). Calculations were performed using (a) exact diagonalization of all eigenstates and eigenvectors for systems up…
Electron spectrum of 2D and 3D antiferromagnetic metals is calculated with account of spin-fluctuation corrections within perturbation theory in the s-f exchange model. Effects of the interaction of conduction electrons with spin waves in…
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-$(1,{1/2})$,…
We present some conjectured approximations for spin expectations in a Quantum Heisenberg system. The conjectures are based on numerical experimentation, some theoretical insights and underpinning, and aesthetic value. We hope theoretical…
For the spin-$\frac{1}{2}$ Heisenberg antiferromagnet on the Kagom\'e lattice we calculate the high temperature series for the specific heat and the structure factor. A comparison of the series with exact diagonalisation studies shows that…
We address the coherence of the dynamics of spin-currents with components transverse to an external magnetic field for the spin-1/2 Heisenberg chain. We study current autocorrelations at finite temperatures and the real-time dynamics of…
We study XXX Heisenberg spin 1/2 anti-ferromagnet. We evaluate a probability of formation of a ferromagnetic string in the anti-ferromagnetic ground state in thermodynamics limit. We prove that for short strings the probability can be…
A full energy spectrum, magnetization and susceptibility of a spin-1/2 Heisenberg model on two edge-shared tetrahedra are exactly calculated by assuming two different coupling constants. It is shown that a ground state in zero field is…
In an effort to understand the low temperature behavior of recently synthesized molecular magnets we present numerical evidence for the existence of a rotational band in systems of quantum spins interacting with nearest-neighbor…
We investigate the thermodynamic properties of the frustrated bilayer quantum Heisenberg antiferromagnet at low temperatures in the vicinity of the saturation magnetic field. The low-energy degrees of freedom of the spin model are mapped…
Quantum magnets with a large SU($N$) symmetry are a promising playground for the discovery of new forms of exotic quantum matter. Motivated by recent experimental efforts to study SU($N$) quantum magnetism in samples of ultracold fermionic…
Antiferromagnetic Heisenberg spin chains with various spin values ($S=1/2,1,3/2,2,5/2$) are studied numerically with the quantum Monte Carlo method. Effective spin $S$ chains are realized by ferromagnetically coupling $n=2S$…