Interplay of electric field and disorder in Dirac liquid silicene

L Craco,S S Carara,S Leoni

doi:10.1140/epjb/s10051-021-00055-5

Abstract

Layered materials with buckled structure offer a promising route to explore distinct phases of quantum matter. Using GGA + DMFT we reveal the complex interplay between perpendicular electric field and site-diagonal disorder in the Dirac liquid electronic state of silicene. The electronic structure we derive is promising in the sense that it leads to results that might explain why out-of-plane electric field plus moderate disorder can generate marginal Dirac valleys consistent with scanning tunneling spectroscopy of silicene on Ag substrates.Graphic

Highlights

Silicene, the silicon-based counterpart of two-dimensional (2D) graphene, has attracted much attention both experimental and theoretically. [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
To further understand the stability of the marginal Dirac liquid electronic state of disordered silicene, in Fig. 6 we display the site-resolved and total generalized gradient approximation (GGA) + DMFT spectral functions obtained using single-zeta (SZ) and double-zeta plus polarization (DZP) basis sets [70]. This is motivated by the fact that the projected GGA DOS within the SZ basis set used to compute the correlated GGA + DMFT spectral functions above introduces a small energy shift of 0.34 eV in the van Hove singularity at the Dirac band edge above EF as compared to DZP: we found that the precise position of the Dirac band edge in the projected GGA DOS depends on the basis set employed in the calculation, with the DZP result giving more accurate agreement between the projected DOS and the bare bandstructure (Fig. 2) of free-standing silicene
An affirmative theoretical answer to electronic structure reconstruction of silicene is shown in Fig. 8, which is in good qualitative agreement with extant STS curves on silicene on Ag substract [3,9,11]

Summary

Introduction

The silicon-based counterpart of two-dimensional (2D) graphene, has attracted much attention both experimental and theoretically. [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. Silicene is a promising candidate to study both massless and massive Dirac fermions under external perturbations like strain and electric field [19,20] It is, expected that by combining many-body electronelectron interactions [10] with out-of-plane electric fields [15,16,21] and local disorder [22,23,24], a wider range of tunability in the electronic structure of silicene might exist. While the Hubbard U in graphene is near to 10.0 eV, the estimate on-site Coulomb repulsion in silicene is 4.77 eV [10], i.e., close to 5.0 eV

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GGA results

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Discussion and conclusion

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