ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                   M E G H Í V Ó - I N V I T A T I O N

    Seminar Series of the Department of Theoretical Physics at the
           Budapest University of Technology and Economics


                          Andreas Schnyder
                           (MPI Stuttgart)


          Three-dimensional topological Dirac materials


Although topologically nontrivial properties are normally associated 
with insulating phases, recent developments have shown that 
(semi)metallic phases can also be topological. In this talk, I will 
survey recent developments regarding the topological classifications of 
(semi)metallic materials in terms of crystal symmetries [1,2]. As a 
concrete examples, I will present results about the recently discovered 
compound Ca3P2 [3], which has a line of Dirac nodes near the Fermi 
energy. I will discuss the topological properties of Ca3P2 in terms of a 
low-energy effective theory and a tight-binding model, derived from ab 
initio DFT calculations. The microscopic model for Ca3P2 shows that the 
drumhead surface states have a rather weak dispersion, which implies 
that correlation effects are enhanced at the surface of Ca3P2. 
Furthermore, I will discuss the parity anomaly that exists in this 
nodal-line semimetal and show how it is connected to unusual transport 
phenomena. If time permits, I will also survey the topological 
properties of the Dirac materials A3EO [4], where A denotes an alkaline 
earth metal, while E stands for Pb or Sn. I will discuss the magnetic 
properties of this Dirac system and show that a strong Zeeman field 
splits the gapped Dirac cones into ungapped Weyl points, which are 
protected by a quantized Chern number.


Időpont: 2016. szeptember 9. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba