Dirac surface states, multiorbital dimerization and superconductivity in Nb- and Ta-based A15 compounds
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2023
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866916661106311168 |
|---|---|
| author | Sattigeri, Raghottam M. Cuono, Giuseppe Hussain, Ghulam Ming, Xing Di Bernardo, Angelo Attanasio, Carmine Cuoco, Mario Autieri, Carmine |
| author_facet | Sattigeri, Raghottam M. Cuono, Giuseppe Hussain, Ghulam Ming, Xing Di Bernardo, Angelo Attanasio, Carmine Cuoco, Mario Autieri, Carmine |
| contents | Using first-principle calculations, we investigate the electronic, topological and superconducting properties of Nb$_3$X (X = Ge, Sn, Sb) and Ta$_3$Y (Y = As, Sb, Bi) A15 compounds. We demonstrate that these compounds host Dirac surface states which are related to a nontrivial Z$_2$ topological value. The spin-orbit coupling (SOC) splits the eightfold degenerate R point close to the Fermi level enhancing the amplitude of the spin Hall conductance. Indeed, despite the moderate spin-orbit of the Nb-compounds, a large spin Hall effect is also obtained in Nb$_3$Ge and Nb$_3$Sn compounds. We show that the Coulomb interaction opens the gap at the R point thus making more evident the occurrence of Dirac surface states. We then investigate the superconducting properties by determining the strength of the electron-phonon BCS coupling. The evolution of the critical temperature is tracked down to the 2D limit indicating a reduction of the transition temperature which mainly arises from the suppression of the density of states at the Fermi level. Finally, we propose a minimal tight-binding model based on three coupled Su-Schrieffer-Heeger chains with t$_{2g}$ Ta- and Nb-orbitals reproducing the spin-orbit splittings at the R point among the $π$-bond bands in this class of compounds. We separate the kinetic parameters in $π$ and $δ$-bonds, in intradimer and interdimer hoppings and discuss their relevance for the topological electronic structure. We point out that Nb$_3$Ge might represent a Z$_2$ topological metal with the highest superconducting temperature ever recorded. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_18245 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Dirac surface states, multiorbital dimerization and superconductivity in Nb- and Ta-based A15 compounds Sattigeri, Raghottam M. Cuono, Giuseppe Hussain, Ghulam Ming, Xing Di Bernardo, Angelo Attanasio, Carmine Cuoco, Mario Autieri, Carmine Superconductivity Materials Science Using first-principle calculations, we investigate the electronic, topological and superconducting properties of Nb$_3$X (X = Ge, Sn, Sb) and Ta$_3$Y (Y = As, Sb, Bi) A15 compounds. We demonstrate that these compounds host Dirac surface states which are related to a nontrivial Z$_2$ topological value. The spin-orbit coupling (SOC) splits the eightfold degenerate R point close to the Fermi level enhancing the amplitude of the spin Hall conductance. Indeed, despite the moderate spin-orbit of the Nb-compounds, a large spin Hall effect is also obtained in Nb$_3$Ge and Nb$_3$Sn compounds. We show that the Coulomb interaction opens the gap at the R point thus making more evident the occurrence of Dirac surface states. We then investigate the superconducting properties by determining the strength of the electron-phonon BCS coupling. The evolution of the critical temperature is tracked down to the 2D limit indicating a reduction of the transition temperature which mainly arises from the suppression of the density of states at the Fermi level. Finally, we propose a minimal tight-binding model based on three coupled Su-Schrieffer-Heeger chains with t$_{2g}$ Ta- and Nb-orbitals reproducing the spin-orbit splittings at the R point among the $π$-bond bands in this class of compounds. We separate the kinetic parameters in $π$ and $δ$-bonds, in intradimer and interdimer hoppings and discuss their relevance for the topological electronic structure. We point out that Nb$_3$Ge might represent a Z$_2$ topological metal with the highest superconducting temperature ever recorded. |
| title | Dirac surface states, multiorbital dimerization and superconductivity in Nb- and Ta-based A15 compounds |
| topic | Superconductivity Materials Science |
| url | https://arxiv.org/abs/2310.18245 |