| Autor: |
Pasquier, Diego, Yazyev, Oleg V. |
| Rok vydání: |
2018 |
| Předmět: |
|
| Zdroj: |
Phys. Rev. B 98, 045114 (2018) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevB.98.045114 |
| Popis: |
The recently investigated $1T$-polymorph of monolayer NbSe$_2$ revealed an insulating behaviour suggesting a star-of-David phase with $\sqrt{13}\,\times\sqrt{13}$ periodicity associated with a Mott insulator, reminiscent of $1T$-TaS$_2$. In this work, we examine this novel two-dimensional material from first principles. We find an instability towards the formation of an incommensurate charge-density-wave (CDW) and establish the star-of-David phase as the most stable commensurate CDW. The mottness in the star-of-David phase is confirmed and studied at various levels of theory: the spin-polarized generalized gradient approximation (GGA) and its extension involving the on-site Coulomb repulsion (GGA+$U$), as well as the dynamical mean-field theory (DMFT). Finally, we estimate Heisenberg exchange couplings in this material and find a weak nearest-neighbour ferromagnetic coupling, at odds with most Mott insulators. We point out the close resemblance between this star-of-David phase and flat-band ferromagnetism models. |
| Databáze: |
arXiv |
| Externí odkaz: |
|
