Incommensurate spin dynamics of high-Tc superconductor YBa2Cu3O7-δ

High energy inelastic neutron scattering measurements were performed in order to elucidate the wave vector and energy dependence of the spin dynamics in YBa2Cu3O6.7 (T-c = 68 K) and YBa2Cu3O7 (T-c = 93 K) by using pulsed neutron techniques. The incommensurability of spin dynamics was clearly observed for the under-doped compound. The peaks appear at (1/2 +/- delta,1/2,0) and (1/2,1/2 +/- delta,0) around the antiferromagnetic zone center of (1/2,1/2,0), The incommensurability delta is 0.11 +/- 0.01 (r.l.u,) for the lower energy region, and the incommensurate peaks seem to merge at about 39 meV. (C) 1999 Elsevier Science Ltd. All rights reserved.