ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Phys Rev Lett. 2013 May 24;110(21):217601. doi: 10.1103/PhysRevLett.110.217601. Epub 2013 May 23.
Quasiparticle dynamics on the topological surface state of Bi(2(3), Bi(2)Te(3), and superconducting Cu(x)Bi(2)Se(3) are studied by 7 eV laser-based angle resolved photoemission spectroscopy. We find strong mode couplings in the Dirac-cone surface states at energies of ~3 and ~15-20 meV associated with an exceptionally large coupling constant λ of ~3, which is one of the strongest ever reported for any material. This result is compatible with the recent observation of a strong Kohn anomaly in the surface phonon dispersion of Bi(2)Se(3), but it appears that the theoretically proposed "spin-plasmon" excitations realized in helical metals are also playing an important role. Intriguingly, the ~3 meV mode coupling is found to be enhanced in the superconducting state of Cu(x)Bi(2)Se(3).
采用 7eV 激光角分辨光发射谱研究了 Bi(2(3), Bi(2)Te(3), 和超导 Cu(x)Bi(2)Se(3)的拓扑表面态上的准粒子动力学。我们发现与耦合常数 λ~3 相关的约 3 和约 15-20meV 的能量处的准粒子动力学在狄拉克锥表面态中存在强模式耦合，这是迄今为止报道的最强耦合常数之一。这一结果与最近在 Bi(2)Se(3)的表面声子色散中观察到的强科恩反常现象相兼容，但似乎理论上提出的在螺旋金属中实现的“自旋等离子体”激发也起着重要作用。有趣的是，在超导状态的 Cu(x)Bi(2)Se(3)中发现约 3meV 的模式耦合增强。
