Two-Dimensionality of Magnetic Excitations on the Trellis Lattice: (La,Sr,Ca)${}_{14}$Cu${}_{24}$O${}_{41}$ and SrCu${}_2$O${}_3$

Abstract

We explore the properties of magnetic excitations on the trellis lattice which is relevant for the so-called telephone-number compounds A${}_{14}$Cu${}_{24}$O${}_{41}$ and the system SrCu${}_2$O${}_3$. The trellis lattice consists of two-leg ladders which are coupled in a strongly frustrated fashion. We use the effective model obtained for a single two-leg spin ladder to calculate the two-dimensional one-triplon dispersion and the corresponding one-triplon contribution to the dynamical structure factor. Special attention is laid on signatures of the frustrating inter-ladder magnetic exchange. A detailed suggestion is made for an experimental detection of this exchange in inelastic neutron scattering experiments.

5 pages, 7 figures, predictions to inelastic neutron experiments; slightly revised version according to the referees' suggestions, in press