Sugawara K, Sato T, Souma S, Takahashi T, Suematsu H
Department of Physics, Tohoku University, Sendai 980-8578, Japan.
Phys Rev Lett. 2007 Jan 19;98(3):036801. doi: 10.1103/PhysRevLett.98.036801. Epub 2007 Jan 16.
We have performed ultrahigh-resolution angle-resolved photoemission spectroscopy on high-quality single crystals of graphite to elucidate the character of low-energy excitations. We found evidence for a well-defined quasiparticle (QP) peak in the close vicinity of the Fermi level comparable to the nodal QP in high-T(c) cuprates, together with the mass renormalization of the band at an extremely narrow momentum region around the K(H) point. Analysis of the QP lifetime demonstrates the presence of strong electron-phonon coupling and linear energy dependence of the QP scattering rate indicative of a marked deviation from the conventional Fermi-liquid theory.
我们对高质量石墨单晶进行了超高分辨率角分辨光电子能谱实验，以阐明低能激发的特性。我们发现，在费米能级附近存在一个定义明确的准粒子（QP）峰，其与高温超导铜酸盐中的节点QP相当，同时在K（H）点周围极窄的动量区域内，能带出现了质量重整化。对QP寿命的分析表明存在强电子-声子耦合，且QP散射率呈线性能量依赖关系，这表明与传统费米液体理论存在显著偏差。
