Group 14 element-based non-centrosymmetric quantum spin Hall insulators with large bulk gap

To date, a number of two-dimensional (2D) topological insulators (TIs) have been realized in Group 14 elemental honeycomb lattices, but all are inversionsymmetric. Here, based on first-principles calculations, we predict a new family of 2D inversion-asymmetric TIs with sizeable bulk gaps from 105 meV to 284 meV, in X2–GeSn (X = H, F, Cl, Br, I) monolayers, making them in principle suitable for room-temperature applications. The nontrivial topological characteristics of inverted band orders are identified in pristine X2–GeSn with X = (F, Cl, Br, I), whereas H2–GeSn undergoes a nontrivial band inversion at 8% lattice expansion. Topologically protected edge states are identified in X2–GeSn with X = (F, Cl, Br, I), as well as in strained H2–GeSn. More importantly, the edges of these systems, which exhibit single-Dirac-cone characteristics located exactly in the middle of their bulk band gaps, are ideal for dissipationless transport. Thus, Group 14 elemental honeycomb lattices provide a fascinating playground for the manipulation of quantum states.

[1]  Baibiao Huang,et al.  Halogenated two-dimensional germanium: candidate materials for being of Quantum Spin Hall state , 2012 .

[2]  E. Krasovskii,et al.  Experimental realization of a three-dimensional topological insulator phase in ternary chalcogenide TlBiSe₂. , 2010, Physical review letters.

[3]  Ying Dai,et al.  Intriguing Behavior of Halogenated Two-Dimensional Tin , 2012 .

[4]  Hasan Sahin,et al.  Monolayer honeycomb structures of group-IV elements and III-V binary compounds: First-principles calculations , 2009, 0907.4350.

[5]  Binghai Yan,et al.  Single Dirac cone topological surface state and unusual thermoelectric property of compounds from a new topological insulator family. , 2010, Physical review letters.

[6]  K. Novoselov,et al.  Control of Graphene's Properties by Reversible Hydrogenation: Evidence for Graphane , 2008, Science.

[7]  Shuichi Murakami,et al.  Quantum spin Hall effect and enhanced magnetic response by spin-orbit coupling. , 2006, Physical review letters.

[8]  Ying Dai,et al.  Strain-induced quantum spin Hall effect in methyl-substituted germanane GeCH3 , 2014, Scientific Reports.

[9]  Cheng-Cheng Liu,et al.  Quantum spin Hall insulators and quantum valley Hall insulators of BiX/SbX (X = H, F, Cl, and Br) monolayers with a record bulk band gap , 2014 .

[10]  G. Sullivan,et al.  Evidence for helical edge modes in inverted InAs/GaSb quantum wells. , 2011, Physical review letters.

[11]  E. J. Mele,et al.  Quantum spin Hall effect in graphene. , 2004, Physical review letters.

[12]  Tanmoy Das,et al.  Prediction of large-gap two-dimensional topological insulators consisting of bilayers of group III elements with Bi. , 2014, Nano letters.

[13]  Thomas Frauenheim,et al.  Robust two-dimensional topological insulators in methyl-functionalized bismuth, antimony, and lead bilayer films. , 2015, Nano letters.

[14]  Thomas Frauenheim,et al.  Robust 2D topological insulators in van der Waals heterostructures. , 2014, ACS nano.

[15]  Xi Dai,et al.  Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface , 2009 .

[16]  Binghai Yan,et al.  Large-gap quantum spin Hall insulators in tin films. , 2013, Physical review letters.

[17]  L. Molenkamp,et al.  Quantum Hall effect from the topological surface states of strained bulk HgTe. , 2011, Physical review letters.

[18]  Z. K. Liu,et al.  Experimental Realization of a Three-Dimensional Topological Insulator , 2010 .

[19]  Cheng-Cheng Liu,et al.  Low-energy effective Hamiltonian involving spin-orbit coupling in silicene and two-dimensional germanium and tin , 2011, 1108.2933.

[20]  H. Monkhorst,et al.  SPECIAL POINTS FOR BRILLOUIN-ZONE INTEGRATIONS , 1976 .

[21]  Bing-Lin Gu,et al.  Functionalized germanene as a prototype of large-gap two-dimensional topological insulators , 2014, 1401.4100.

[22]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[23]  R. Arita,et al.  Emergence of non-centrosymmetric topological insulating phase in BiTeI under pressure , 2011, Nature Communications.

[24]  Shou-Cheng Zhang,et al.  Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells , 2006, Science.

[25]  G. Scuseria,et al.  Hybrid functionals based on a screened Coulomb potential , 2003 .

[26]  G. Barber,et al.  Graphane: a two-dimensional hydrocarbon , 2006, cond-mat/0606704.

[27]  Joel E Moore,et al.  The birth of topological insulators , 2010, Nature.

[28]  R. Cava,et al.  Observation of a large-gap topological-insulator class with a single Dirac cone on the surface , 2009 .

[29]  E. Akturk,et al.  Two- and one-dimensional honeycomb structures of silicon and germanium. , 2008, Physical review letters.

[30]  Z. Hussain,et al.  Discovery of a single topological Dirac fermion in the strong inversion asymmetric compound BiTeCl , 2013, Nature Physics.

[31]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[32]  C. Felser,et al.  A large-energy-gap oxide topological insulator based on the superconductor BaBiO3 , 2013, Nature Physics.

[33]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[34]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[35]  X. Dai,et al.  Transition-Metal Pentatelluride ZrTe 5 and HfTe 5 : A Paradigm for Large-Gap Quantum Spin Hall Insulators , 2013, 1309.7529.

[36]  L. Molenkamp,et al.  Quantum Spin Hall Insulator State in HgTe Quantum Wells , 2007, Science.

[37]  C. Kane,et al.  Topological Insulators , 2019, Electromagnetic Anisotropy and Bianisotropy.

[38]  L. Fu,et al.  Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides , 2014, 1406.2749.

[39]  Ping Li,et al.  Epitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface , 2014, Proceedings of the National Academy of Sciences.

[40]  Ashvin Vishwanath,et al.  Subject Areas : Strongly Correlated Materials A Viewpoint on : Topological semimetal and Fermi-arc surface states in the electronic structure of pyrochlore iridates , 2011 .

[41]  L. Fu,et al.  Quantum spin Hall effect in two-dimensional transition metal dichalcogenides , 2014, Science.

[42]  Cheng-Cheng Liu,et al.  Quantum spin Hall effect in silicene and two-dimensional germanium. , 2011, Physical review letters.