In two dimensions, wherever two bands cross one in essence has a cone-like energy dispersion centred on the point of degeneracy in the k space. How close this energy dispersion is to an ideal cone, depends on the symmetry of the relevant k point. How extensive this region is, depends on the nearby energy dispersions. Physically, it is important where the energy of the degenerate levels is located with respect to the chemical potential.
Dear Ali,
Yes it is possible to have a Dirac cone forme by orbitals of different kind of atoms.
The simplest symmetry protecting the topology associated to the singularities introduced is the time reversal symmetry which allows to form Kramers pairs.
thanks, for your answers. Daniel Baldomir can you please provide me any reference for it? Actually, in my system, I am getting the same and I need a good reference to justify it.
Dear Alí,
If you go to my contributions you can find one Phys.Rev.B and I hope that this can help you.
Ab initio study of Z2topological phases in(SrTiO3)7/(SrIrO3)2 and (KTaO3)7/(KPtO3)2
multilayers
J. L. Lado,1, 2,∗V. Pardo,1, 2,†and D. Baldomir1, 21
Departamento de F ́ısica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
2
Instituto de Investigaci ́ons Tecnol ́oxicas, Universidade de
Santiago de Compostela, E-15782 Santiago de Compostela, Spain
(Dated: June 11, 2013)
Honeycomb structures formed by the growth of perovskite 5d transition metal oxide heteroestructures along the (111) direction int 52g
configuration can give rise to topological ground states characterized by a topological indexν=1. Using a combination of a tight binding model and ab initio
calculations we study the multilayers (SrTiO3)7/(SrIrO3)2 and (KTaO3)7/(KPtO3)2 as a function of parity asymmetry, on-site interaction and uniaxial strain and determine the nature and evolutionof the gap. (SrTiO3)7/(SrIrO3)2is found to be a topological semimetal. (KTaO3)7/(KPtO3)2 is a topological Mott insulator that can be driven to a trivial insulating phase by an external electric field.
Ab initio study of Z_{2} topological phases in perovskite (111) (SrTiO_{3})_{7}/(SrIrO_{3})_{2} and (KTaO_{3})_{7}/(KPtO_{3})_{2} multilayers. Available from: https://www.researchgate.net/publication/258781968_Ab_initio_study_of_Z_2_topological_phases_in_perovskite_111_SrTiO_3_7SrIrO_3_2_and_KTaO_3_7KPtO_3_2_multilayers [accessed Sep 27, 2017].
Article Ab initio study of Z_{2} topological phases in perovskite (1...
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