Hou Chang-Yu, Chamon Claudio, Mudry Christopher
Physics Department, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
Phys Rev Lett. 2007 May 4;98(18):186809. doi: 10.1103/PhysRevLett.98.186809.
Electron fractionalization is intimately related to topology. In one-dimensional systems, fractionally charged states exist at domain walls between degenerate vacua. In two-dimensional systems, fractionalization exists in quantum Hall fluids, where time-reversal symmetry is broken by a large external magnetic field. Recently, there has been a tremendous effort in the search for examples of fractionalization in two-dimensional systems with time-reversal symmetry. In this Letter, we show that fractionally charged topological excitations exist on graphenelike structures, where quasiparticles are described by two flavors of Dirac fermions and time-reversal symmetry is respected. The topological zero modes are mathematically similar to fractional vortices in p-wave superconductors. They correspond to a twist in the phase in the mass of the Dirac fermions, akin to cosmic strings in particle physics.
电子分数化与拓扑结构密切相关。在一维系统中，简并真空之间的畴壁处存在分数电荷态。在二维系统中，量子霍尔流体中存在分数化现象，其中时间反演对称性被强外磁场打破。最近，人们付出了巨大努力来寻找具有时间反演对称性的二维系统中分数化的例子。在本信函中，我们表明在类石墨烯结构上存在分数电荷拓扑激发，其中准粒子由两种味的狄拉克费米子描述且时间反演对称性得以保持。拓扑零模在数学上类似于p波超导体中的分数涡旋。它们对应于狄拉克费米子质量相位中的扭转，类似于粒子物理学中的宇宙弦。
