Hwang Jungseek, Timusk Thomas, Carbotte Jules P
Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada.
Nature. 2007 Mar 8;446(7132):E3-4. doi: 10.1038/nature05709.
The study of bosonic modes that couple to the charge carriers is a key element in understanding superconductivity. Using atomic-resolution scanning-tunnelling microscopy (STM) to extract the spectrum of these modes in the high-temperature superconductor Bi2Sr2CaCu2O(8+delta), Lee et al. find a mode whose frequency does not depend on doping but that changes on isotopic substitution of 16O with 18O. From this, they infer a role for lattice modes (phonons). However, examination of their data reveals a weaker, but distinct, feature that has all the characteristics of the magnetic excitation identified as the bosonic mode in other competing experiments. We therefore suggest that the lattice mode seen by Lee et al. is not relevant to superconductivity and is due to inelastic tunnelling through the insulating oxide layer.
对与电荷载流子耦合的玻色子模式的研究是理解超导性的关键要素。利用原子分辨率扫描隧道显微镜（STM）来提取高温超导体Bi2Sr2CaCu2O(8+δ)中这些模式的频谱，李等人发现了一种模式，其频率不依赖于掺杂，但在16O被18O同位素取代时会发生变化。据此，他们推断出晶格模式（声子）的作用。然而，对他们数据的检查揭示了一个较弱但明显的特征，该特征具有在其他竞争实验中被确定为玻色子模式的磁激发的所有特征。因此，我们认为李等人所看到的晶格模式与超导性无关，而是由于通过绝缘氧化层的非弹性隧穿所致。
