2016/09/30 by Steve M. Young, Steve M Young, Benjamin J. Wieder
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Condensed matter physics #Dirac (video compression format) #Dirac fermion #Fermion #Geometry #Graphene research and applications #Homogeneous space #Phase transition #Physics #Quantum mechanics #Quantum phase transition #Quantum phases #Semimetal #Topological Materials and Phenomena #Weyl semimetal #cond-mat.mes-hall #cond-mat.other
paper · pdf · doi:10.1103/physrevlett.118.186401
published as Phys. Rev. Lett. 118, 186401 (2017)
openalex publication_date 2017/05/04 · arxiv created 2017/05/24 · arxiv updated 2017/05/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Filling-enforced Dirac semimetals, or those required at specific fillings by the combination of crystalline and time-reversal symmetries, have been proposed in numerous materials. However, Dirac points in these materials are not generally robust against breaking or modifying time-reversal symmetry. We present a new class of two-dimensional Dirac semimetal protected by the combination of crystal symmetries and a special, antiferromagnetic time-reversal symmetry. Systems in this class of magnetic layer groups, while having broken time-reversal symmetry, still respect the operation of time-reversal followed by a half-lattice translation. In contrast to 2D time-reversal-symmetric Dirac semimetal phases, this magnetic Dirac phase is capable of hosting just a single isolated Dirac point at the Fermi level, one that can be stabilized solely by symmorphic crystal symmetries. We find that this Dirac point represents a new quantum critical point, existing at the boundary between Chern insulating, antiferromagnetic topological crystalline insulating, and trivial insulating phases, and we discuss its relationship with condensed matter fermion doubling theorems. We present density functional theoretic calculations which demonstrate the presence of these 2D magnetic Dirac points in FeSe monolayers and discuss the implications for engineering quantum phase transitions in these materials.