We report the highly anisotropic Dirac fermions in a Bi square net of SrMnBi2, based on a first principle calculation, angle resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the (SrBi)+ layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in SrMnBi2 is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of ~ 8. These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provide a new platform that hosts highly anisotropic Dirac fermions.
@article{arxiv.1104.5138,
title = {Anisotropic Dirac fermions in a Bi square net of SrMnBi2},
author = {Joonbum Park and G. Lee and F. Wolff-Fabris and Y. Y. Koh and M. J. Eom and Y. K. Kim and M. A. Farhan and Y. J. Jo and C. Kim and J. H. Shim and J. S. Kim},
journal= {arXiv preprint arXiv:1104.5138},
year = {2013}
}