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Title: Integrating superconducting phase and topological crystalline quantum spin Hall effect in hafnium intercalated gallium film

Here, motivated by the growth of superconducting atomic hexagonal Ga layers on GaN surface we have calculated the electronic properties of Hf intercalated honeycomb Ga layers using first-principles theory. In contrast to the hexagonal Ga layers where substrate is necessary for their stability, we find the above structure to be dynamically stable in its freestanding form with small formation energy. In particular, six Dirac cones composed of Hf- dxy/ dx2-y2 orbitals are observed in the first Brillouin zone, slightly below the Fermi energy. Spin-orbit coupling opens a large band gap of 177 meV on these Dirac cones. By calculating its mirror Chern number, we demonstrate that this band gap is topologically nontrivial and protected by mirror symmetry. Such mirror symmetry protected band gaps are rare in hexagonal lattice. A large topological crystalline quantum spin Hall conductance σ SH ~–4 e 2/h is also revealed. Moreover, electron-phonon coupling calculations reveal that this material is superconducting with a transition temperature Tc = 2.4 K, mainly contributed by Ga out-of-plane vibrations. Our results provide a route toward manipulating quantum spin Hall and superconducting behaviors in a single material which helps to realize Majorana fermions and topological superconductors.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Virginia Commonwealth Univ., Richmond, VA (United States)
  2. Peking Univ., Beijing (China)
  3. Peking Univ., Beijing (China); Virginia Commonwealth Univ., Richmond, VA (United States)
Publication Date:
Grant/Contract Number:
FG02-96ER45579; FG02-11ER46827
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 25; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Virginia Commonwealth Univ., Richmond, VA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1467580
Alternate Identifier(s):
OSTI ID: 1258325

Zhou, Jian, Zhang, Shunhong, Wang, Qian, and Jena, Puru. Integrating superconducting phase and topological crystalline quantum spin Hall effect in hafnium intercalated gallium film. United States: N. p., Web. doi:10.1063/1.4954672.
Zhou, Jian, Zhang, Shunhong, Wang, Qian, & Jena, Puru. Integrating superconducting phase and topological crystalline quantum spin Hall effect in hafnium intercalated gallium film. United States. doi:10.1063/1.4954672.
Zhou, Jian, Zhang, Shunhong, Wang, Qian, and Jena, Puru. 2016. "Integrating superconducting phase and topological crystalline quantum spin Hall effect in hafnium intercalated gallium film". United States. doi:10.1063/1.4954672. https://www.osti.gov/servlets/purl/1467580.
@article{osti_1467580,
title = {Integrating superconducting phase and topological crystalline quantum spin Hall effect in hafnium intercalated gallium film},
author = {Zhou, Jian and Zhang, Shunhong and Wang, Qian and Jena, Puru},
abstractNote = {Here, motivated by the growth of superconducting atomic hexagonal Ga layers on GaN surface we have calculated the electronic properties of Hf intercalated honeycomb Ga layers using first-principles theory. In contrast to the hexagonal Ga layers where substrate is necessary for their stability, we find the above structure to be dynamically stable in its freestanding form with small formation energy. In particular, six Dirac cones composed of Hf-dxy/dx2-y2 orbitals are observed in the first Brillouin zone, slightly below the Fermi energy. Spin-orbit coupling opens a large band gap of 177 meV on these Dirac cones. By calculating its mirror Chern number, we demonstrate that this band gap is topologically nontrivial and protected by mirror symmetry. Such mirror symmetry protected band gaps are rare in hexagonal lattice. A large topological crystalline quantum spin Hall conductance σSH ~–4 e2/h is also revealed. Moreover, electron-phonon coupling calculations reveal that this material is superconducting with a transition temperature Tc = 2.4 K, mainly contributed by Ga out-of-plane vibrations. Our results provide a route toward manipulating quantum spin Hall and superconducting behaviors in a single material which helps to realize Majorana fermions and topological superconductors.},
doi = {10.1063/1.4954672},
journal = {Applied Physics Letters},
number = 25,
volume = 108,
place = {United States},
year = {2016},
month = {6}
}