An overview of one-and two-dimensional quantum spin systems based on transition-metal
oxides and halides of current interest is given, such as spin-Peierls, spin-dimer …

This article summarizes and extends the recent developments in the microscopic modeling
of the magnetic excitations in cuprate two-leg ladder systems. The microscopic Hamiltonian …

For many-particle systems defined on lattices we investigate the global structure of effective
Hamiltonians and observables obtained by means of a suitable basis transformation. We …

We provide analytical and numerical insights into the phase diagram and other properties of
the extended Kitaev-Heisenberg model on the honeycomb lattice in the easy-plane limit, in …

Phonon-assisted two-magnon absorption is studied in the spin-1/2 two-leg ladders of (Ca,
La) 14 Cu 24 O 41 for E∥ c (legs) and E∥ a (rungs). We verify the theoretically predicted …

Raman light scattering of the two-dimensional quantum spin system SrCu 2 (BO 3) 2 shows
a rich structure in the magnetic excitation spectrum, including several well-defined bound …

Spectral densities are computed in unprecedented detail for quantum antiferromagnetic spin
1/2 two-leg ladders. These results were obtained due to a major methodical advance …

We present a new linked cluster expansion for calculating properties of multiparticle
excitation spectra to high orders. We use it to obtain the two-particle spectra for systems of …

We analyze the stability of the spontaneously dimerized phase of the frustrated Heisenberg
antiferromagnet—the J 1− J 2 model—in two dimensions. The lowest triplet excitation …

Quantum antiferromagnets have proven to be some of the cleanest realizations available for
theoretical, numerical, and experimental studies of quantum fluctuation effects. At finite …