Short wavelength spin excitations in the HTc-cuprates

✍ Scribed by P. Knoll; U. Hohenester; S. Lo

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 144 KB
• Volume: 194-196
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/0921-4526(94)91576-8

✦ Synopsis

The short wavelength behavior of spin excitations has been investigated by means of 2-magnon Raman spectroscopy in YBa2Cu306+ x , La2CuO4, and Nd2CuO 4. The resonance behavior indicates a scattering mechanism via a Cu-3d O-2p charge tran.qfer excitation. In the undoped material the temperature dependence of 2-magnon scattering is interpreted in terms of magnon-phonon interaction. Upon doping towards the insulator-metal transition the short-wavelength spin excitations renormalize to lower energies and damp significantly. The ratio of ima~nary part to real part of zone edge-spin-excitations upon doping has been quantitatively determined and is found to be in the range of 4-6 for all investigated HTc cuprates. Simple spin wave cluster estimates seem to rule out that this behavior can be explained by simple static anti ferromagnetic cluster-size effects.