laboratoire pierre aigrain
électronique et photonique quantiques
 
laboratoire pierre aigrain
 

Séminaire Jeune, 21 octobre 2015

Thanyanan Phuphachong
Massive and Massless Dirac Fermions in PbSnTe Topological Crystalline Insulator probed by Magneto-optical Absorption

Dirac fermions in condensed matter physics hold great promise for novel fundamental physics, quantum device and data storage applications. Our research focuses on the electronic and magneto-optical properties of Dirac fermions in a novel class of materials : topological crystalline insulator (TCI). TCIs possess insulative bulk states and metallic surface states protected by mirror symmetry of the crystal [1]. Narrow gap rocksalt IV-VI semiconductors such as Pb1-xSnxTe or Pb1-xSnxSe were shown to exhibit massless topological surface Dirac fermions for the Sn content above the critical value [2], as well as massive bulk Dirac fermions.

Under a strong magnetic field (B), both surface and bulk states are quantized into Landau levels which are B1/2-dependent, and are thus difficult to distinguish. In this work, magneto-optical absorption is used to probe the Landau levels of high mobility Bi-doped Pb1-xSnxTe (111)-oriented epilayers. The high mobility achieved in these thin film structures allows us to probe and distinguish the Landau levels of both surface and bulk Dirac fermions. The detailed analysis and quantitative information extracted from Landau levels transitions of surface and bulk states will be discussed in the seminar.

Keywords : Dirac fermions, topological crystalline insulators, topological surface states, magneto-optical absorption, Landau levels

References :
[1] Fu, L. Topological Crystalline Insulators. Phys. Rev. Lett. 106, 106802 (2011).
[2] Ando, Y. & Fu, L. Topological Crystalline Insulators and Topological Superconductors  : From Concepts to Materials. Annu. Rev. Condens. Matter Phys. 6, 361-381 (2015).