Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study
Under the density functional theory framework, we have calculated the electronic and elastic properties of APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inl...
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doaj-8374626ca64746b287b6108640a79aff2021-01-27T00:06:05ZengMDPI AGApplied Sciences2076-34172021-01-01111143114310.3390/app11031143Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio StudyChi-Hsuan Lee0Jen-Chuan Tung1Graduate Institute of Applied Physics, National Chengchi University, Taipei 11605, TaiwanCenter for General Education, China Medical University, Taichung 40402, TaiwanUnder the density functional theory framework, we have calculated the electronic and elastic properties of APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> (A = Be, Mg, Ca, Sr, Ba, and Ra) cubic perovskites. We found that CaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, SrPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, BaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, and RaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> are topological insulators (TIs) with very large bandgaps of 0.861, 0.871, 0.820, and 0.810 eV, respectively. The nontrivial band topology together with the Z<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> topological number of APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite are investigated. We also theoretically determine the three independent elastic constants C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>11</mn></msub></semantics></math></inline-formula>, C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>12</mn></msub></semantics></math></inline-formula>, and C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>44</mn></msub></semantics></math></inline-formula> of the APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite. The bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and anisotropy factor are also calculated from the obtained elastic constants. We found that the Debye temperature for the APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite is around 330-370 K. In the bulk APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite, if the center Po atom is shifted 0.09Å away from the center, the induced electric polarization is quite large, being around 0.02 C/m<inline-formula><math display="inline"><semantics><msup><mrow></mrow><mn>2</mn></msup></semantics></math></inline-formula>. In the surface band calculation, we found that both AO and PoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> surfaces give rise to contributions to the conduction channel. If the Po atom moves both in-plane and out-of-plane, we show that both electric polarization and topologically protect surface conduction states exist in APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite, indicating that these oxide APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskites are ferroelectric TIs and might be useful for spintronic applications.https://www.mdpi.com/2076-3417/11/3/1143topological insulatorsdensity functional theoryelectric polarization |
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language |
English |
format |
Article |
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author |
Chi-Hsuan Lee Jen-Chuan Tung |
spellingShingle |
Chi-Hsuan Lee Jen-Chuan Tung Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study Applied Sciences topological insulators density functional theory electric polarization |
author_facet |
Chi-Hsuan Lee Jen-Chuan Tung |
author_sort |
Chi-Hsuan Lee |
title |
Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study |
title_short |
Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study |
title_full |
Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study |
title_fullStr |
Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study |
title_full_unstemmed |
Large Bandgap Topological Insulator in Oxide APoO<sub>3</sub> (A = Be, Mg, Ca, Sr, Ba, and Ra) Perovskite: An Ab Initio Study |
title_sort |
large bandgap topological insulator in oxide apoo<sub>3</sub> (a = be, mg, ca, sr, ba, and ra) perovskite: an ab initio study |
publisher |
MDPI AG |
series |
Applied Sciences |
issn |
2076-3417 |
publishDate |
2021-01-01 |
description |
Under the density functional theory framework, we have calculated the electronic and elastic properties of APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> (A = Be, Mg, Ca, Sr, Ba, and Ra) cubic perovskites. We found that CaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, SrPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, BaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>, and RaPoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> are topological insulators (TIs) with very large bandgaps of 0.861, 0.871, 0.820, and 0.810 eV, respectively. The nontrivial band topology together with the Z<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> topological number of APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite are investigated. We also theoretically determine the three independent elastic constants C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>11</mn></msub></semantics></math></inline-formula>, C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>12</mn></msub></semantics></math></inline-formula>, and C<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>44</mn></msub></semantics></math></inline-formula> of the APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite. The bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and anisotropy factor are also calculated from the obtained elastic constants. We found that the Debye temperature for the APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite is around 330-370 K. In the bulk APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite, if the center Po atom is shifted 0.09Å away from the center, the induced electric polarization is quite large, being around 0.02 C/m<inline-formula><math display="inline"><semantics><msup><mrow></mrow><mn>2</mn></msup></semantics></math></inline-formula>. In the surface band calculation, we found that both AO and PoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> surfaces give rise to contributions to the conduction channel. If the Po atom moves both in-plane and out-of-plane, we show that both electric polarization and topologically protect surface conduction states exist in APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskite, indicating that these oxide APoO<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula> perovskites are ferroelectric TIs and might be useful for spintronic applications. |
topic |
topological insulators density functional theory electric polarization |
url |
https://www.mdpi.com/2076-3417/11/3/1143 |
work_keys_str_mv |
AT chihsuanlee largebandgaptopologicalinsulatorinoxideapoosub3subabemgcasrbaandraperovskiteanabinitiostudy AT jenchuantung largebandgaptopologicalinsulatorinoxideapoosub3subabemgcasrbaandraperovskiteanabinitiostudy |
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