Threedimensional topological Dirac materials
DIPC Seminars
 Speaker

Dr. Andreas Schnyder, Max Planck Institute for Solid State Research
 When

2016/10/27
14:00  Place
 Donostia International Physics Center
 Add to calendar
 iCal
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 lowenergy effective theory and a tightbinding model,
derived from abinitio 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 nodalline semimetal and
show how it is connected to unusual transport phenomena. As a second example,
I will 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. If time permits, I will also
present some results about noncentrosymmetric superconductors and their
Majorana flatband surface states.
[1] ChingKai Chiu, Andreas P. Schnyder, Phys. Rev. B 90, 205136 (2014).
[2] Y. X. Zhao, Andreas P. Schnyder, Z. D. Wang, Phys. Rev. Lett. 116, 156402
(2016).
[3] Y.H. Chan, ChingKai Chiu, M. Y. Chou, A. P. Schnyder, Phys. Rev. B 93,
205132 (2016).
[4] ChingKai Chiu, Y.H. Chan, Xiao Li, Y. Nohara, A. P. Schnyder ,
arXiv:1606.03456 (submitted).