Neutron-scattering study on the spin-Peierls transition in a quasi-one-dimensional magnetCuGeO3

Abstract

We experimentally show that in the inorganic spin-Peierls compound ${\mathrm{CuGeO}}_3$ the inelastic-neutron-scattering intensity with ΔE=1 meV at (0,1,0.5) exponentially decreases below ${\mathit{T}}_{\mathrm{SP}}$(=14 K) due to the formation of the spin-Peierls gap. We also found that the magnetic excitation spectrum exhibits a pronounced energy dispersion, the intrachain and interchain exchange parameters ${\mathit{J}}_{\mathit{c}}$≊10.4 meV, ${\mathit{J}}_{\mathit{b}}$≊0.1${\mathit{J}}_{\mathit{c}}$, and ${\mathit{J}}_{\mathit{a}}$≊-0.01${\mathit{J}}_{\mathit{c}}$, and the gap energy at T=0 K is 2.1 meV, suggesting that ${\mathit{J}}_{\mathit{b}}$/${\mathit{J}}_{\mathit{c}}$≊0.1 is rather large compared to the organic spin-Peierls system.