Dynamic properties of quantum spin chains

Artur Barasiński, Bartosz Brzostowski, R. Matysiak +2 more

Oleg Derzhko, Taras Krokhmalskii, Taras Verkholyak

Gerhard M�ller

M. Topilko, Oleg Derzhko, Taras Krokhmalskii

We consider the spin-1/2 isotropic XY chain in a transverse field with three-site interactions of (XZY -Y ZX)--type, which can be transformed into a system of noninteracting spinless fermions.We study dynamic properties of the spin model.In particular, we calculate the dynamic structure factors which are governed by a two-fermion excitation continuum.We demonstrate how the three-site interactions manifest themselves in the dynamic properties of the quantum spin chain.

Jill C. Bonner, John B. Parkinson

Taras Verkholyak, Oleg Derzhko, Taras Krokhmalskii +1 more

We examine dynamic structure factors of spin-$1∕2$ chains with nearest-neighbor interactions of $XX$ and Dzyaloshinskii-Moriya type and with periodic and random changes in the sign of these interactions. This special kind of inhomogeneity can be eliminated from the Hamiltonian by suitable transformation of the spin variables. As a result, the dynamic structure factors of periodic or random chains can be computed from those of the uniform chains. Using the exact analytical and precise numerical results available for the uniform systems, we illustrate the effects of regular alternation or random disorder on dynamic structure factors of quantum spin chains.