Topological

After the discovery of 2D and 3D topological insulators, the topological semi metallic phase attracted more research interest as their peculier band crossing in the bulk and the existence of strange surface state. More recently a new fermion known as triple point fermion is observed as a topological quasi particle in condensed matter system which do not have any corresponding fermion in the high energy physics.  Based on first principle theoretical calculation we have predicted several candidate materials for triple point fermion (TPF) in Heusler compounds X2YZ with space group Fm-3m. Due to the existence of three fold symmetry and mirror symmetry in these systems, a triple degenerate crossing can be realized along some specific high symmetry line and at high symmetric point. The binding energy of this TPF can be varied by appropriate alloying. Under spin orbit coupling each TPF splits into two dirac fermion of type-I (Linear band crossing) and type-II (Quadratic band crossing).

References

  1. R. Barik, R. Shinde, and A. K. Singh, Multiple Triple-Point Fermions in Heusler Compounds J. Phys. Cond. Mat. In press (2018)
  2. R. Juneja, R. Shinde, and A. K. Singh, Pressure-Induced Topological Phase Transitions in CdGeSb2 and CdSnSb2 J. Phys. Chem. Lett. 9, 2202 (2018)
  3. J. S. Kim, R. Juneja, N. P. Salke, W. Palosz, V. Swaminathan, S. Trivedi, A. K. Singh, D. Akinwande and J. Lin, Structural, Vibrational, and Electronic Topological Transitions of Bi1.5Sb0.5Te1.8Se1.2 under Pressure J. Appl. Phys. 123, 115903 (2018)
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