NEUTRON-SCATTERING STUDY ON THE SPIN-PEIERLS TRANSITION IN A QUASI-ONE-DIMENSIONAL MAGNET CUGEO3

We experimentally show that in the inorganic spin-Peierls compound CuGeO3 the inelastic-neutron-scattering intensity with DELTAE = 1 meV at (0,1,0.5) exponentially decreases below T(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 J(c) almost-equal-to 10.4 meV, J(b) almost-equal-to 0.1J(c), and J(a) almost-equal-to -0.01J(c), and the gap energy at T = 0 K is 2.1 meV, suggesting that J(b)/J(c) almost-equal-to 0.1 is rather large compared to the organic spin-Peierls system.