Speaker
Description
Quantum spin Hall phase, or also referred as Topological Insulator state, has been obtained in 2007 in a CdTe/HgTe quantum well [1]. These novel state is possible due to the inverted band order near the Fermi energy. These behaviour is originated because there exist a non negligible correlation between valence electrons of the 5d- and 6s-orbital of Hg [2], and relativistic effects [3], specifically spin-orbit coupling [4].
In this wotk, we present the electronic structure of Cadmiun Telluride (CdTe) and Mercury Teluride (HgTe), obtained using the local spin density approximation, including the Hubbard correction (LSDA+U), in the density functional theory (DFT), considering non relativistic, relativistic, and relativistic with spin-orbit coupling effects for each alloy. The results show that relativistic effects reduce the band gap for materials alloys, and inverted band ordering for HgTe is only possibe if spin-orbit copupling is considered.
References
[1] König, Markus, et al. "Quantum spin Hall insulator state in HgTe quantum wells." Science 318.5851 (2007): 766-770..
[2] Hotta, Takashi. "Orbital ordering phenomena in d-and f-electron systems." Reports on Progress in Physics 69.7 (2006): 2061.
[3] Singh, Prabhakar P. "Relativistic effects in mercury: Atom, clusters, and bulk." Physical Review B 49.7 (1994): 4954.
[4] Al-Rajoub, S., and B. Hamad. "Theoretical investigations of the structural, electronic and optical properties of $Hg_{1-x}Cd_{x}Te$ alloys." Philosophical Magazine 95.22 (2015): 2466-2481.
