Two-chain spin ladder with frustrating second-neighbor interactions

Abstract

The Heisenberg model on a two-chain spin-$\frac{1}{2}$ ladder with frustrating second-neighbor interactions is studied by using series expansions about the Ising and dimer limits, numerical diagonalization, and by Abelian bosonization analysis. The phase diagram is determined, and pair correlations and the complete dispersion relations for the triplet spin-wave excitations are also computed.