1202.5636 (Zhijun Wang et al.)

Marginal Fermi Points and Topological Phase Transitions in Dirac
Semimetal $A_3$Bi ($A$=Na, K, Rb)    [PDF]

Zhijun Wang, Yan Sun, Xingqiu Chen, Cesare Franchini, Gang Xu, Hongming Weng, Xi Dai, Zhong Fang

The vacuum of Standard Model above electroweak transition can be regarded as a system with marginal Fermi points (MFP), which is not stable and may decay into three topologically distinct universality classes, i.e., vacua with gap, fermi surfaces, or Weyl points. We expect that, condensed matters with emerging relativistic quantum field theory in the low energy corner, may be relevant to such physics as well. Here we show, based on first-principles calculations, that crystalline $A_3$Bi ($A$=Na, K, Rb) are three dimensional (3D) Dirac semimetals with MFP protected by crystal symmetry. They possess non-trivial Fermi arcs on the surfaces, and can be driven into various topologically distinct phases by explicit breaking of symmetries. Giant diamagnetism, linear quantum magnetoresistance, and quantum spin-Hall effect will be expected for such novel compounds.

View original: http://arxiv.org/abs/1202.5636