Abstract
We report the observation of highly anisotropic Dirac fermions in a Bi square net of , based on a first-principles calculation, angle-resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of . These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provides a new platform that hosts highly anisotropic Dirac fermions.
- Received 27 April 2011
DOI:https://doi.org/10.1103/PhysRevLett.107.126402
© 2011 American Physical Society