Low-temperature linear transport of two-dimensional massive Dirac fermions in silicene: Residual conductivity and spin/valley Hall effects

Abstract

Considering finite-temperature screened electron-impurity scattering, we present a kinetic equation approach to investigate transport properties of two-dimensional massive fermions in silicene. We find that the longitudinal conductivity is always nonvanishing when chemical potential lies within the energy gap. This residual conductivity arises from interband correlation and strongly depends on strength of electron-impurity scattering. We also clarify that the electron-impurity interaction makes substantial contributions to the spin and valley Hall conductivities, which, however, are almost independent of impurity density. The dependencies of longitudinal conductivity as well as of spin and valley Hall conductivities on chemical potential, temperature, and gap energy are analyzed.

Dirac cone pairs in silicene induced by interface Si-Ag hybridization: A first-principles effective band study

“…Silicene is a promising candidate material for developing next generation field effect transistors [1][2][3][4][5][6][7][8][9][10][11][12][13][14], valleytronic devices and quantum spin Hall devices [36][37][38][39][40][41], thanks to its relatively strong spin-orbital coupling and compatibility with silicon based technology. These applications are closely associated with the presence of Dirac electrons in free-standing silicene predicted from theory [42].…”

Effects of electron-impurity scattering on density of states in silicene: Impurity bands and band-gap narrowing

“…56 On the other hand, in silicene, the interband correlation induced by electron-impurity scattering is quite important: it leads to residual conductivity when the density of carriers in silicene essentially vanishes. 31 Hence, to evaluate the Green's function, generalizing the one-band multiple-scattering method to the two-band case with consideration of interband correlation is required.…”

“…In experiment, silicene has been successfully fabricated via epitaxial growth on the Ag(111), 5,9,16,19,20 ZrB 2 (0001), 10 ZrC(111), 27 Ir(111), 25 and MoS 2 surfaces 28 and the silicene field effect transistor (FET) operating at room temperature has also been realized very recently. 32 In theory, many interesting phenomena in silicene, such as the phase transition from a quantum spin-Hall state to a trivial insulating state 7,13,14,[21][22][23]26 , the intrinsic spin-Hall and valley-Hall effects induced by ac and dc electric field 23,26,31 , etc. have been predicted.…”

Nonlinear electrical transport properties in silicene

“…Recently, the low-temperature linear transport of massive Dirac carriers in single-layer silicene by only considering the screened electron-impurity is studied [17]. It is found that the longitudinal conductivity is strongly affected by the tunable gap energy.…”

“…with Z i being the impurity charge number (assumed to be 1 in the calculation), κ as the dielectric constant of the substrate, ε(q) denoting the static dielectric function in the random phase approximation, the form of which can be found in refs. [17,19,26]. The impurity density is chosen to be n i = 5 × 10 12 m −2 .…”