Abstract
We have performed inelastic-neutron-scattering and dc susceptibility measurements on a polycrystalline sample of , which has a complex crystal structure comprising alternating layers containing isolated Cu chains and two-legged ladders. The observed excitation spectrum is consistent with a spin gap for the ladder of 35 meV. At lower energy transfers we have observed a broad, nondispersive, feature centered on 10 meV that corresponds to singlet-triplet excitations in the Cu chains. We see some evidence in our susceptibility and neutron-scattering measurements to suggest that portions of the Cu chains are dimerized, or broken up into larger finite chains by nonmagnetic Cu units.
- Received 4 March 1996
DOI:https://doi.org/10.1103/PhysRevB.53.R14721
©1996 American Physical Society