1202.1357 (Motohiko Ezawa)

Quantum Hall Effects in Silicene    [PDF]

Motohiko Ezawa

We investigate quantum Hall effects in silicene by applying electric field
$E_z$ parallel to magnetic field. Silicene is a monolayer of silicon atoms
forming a two-dimensional honeycomb lattice, and shares almost every remarkable
property with graphene. A new feature is its buckled structure, due to which
the band structure can be controlled externally by changing $E_z$. The low
energy physics of silicene is described by massive Dirac fermions, where the
mass is a function of $E_z$ and becomes zero at the critical field
$E_{\text{cr}}$. We show that there are no zero energy states due to the Dirac
mass term except at the critical electric field $E_{\text{cr}}$. Furthermore it
is shown that the 4-fold degenerate zero-energy states are completely resolved
even without considering Coulomb interactions. These features are highly
contrasted with those in graphene, demonstrating that silicene has a richer
structure. The prominent feature is that, by applying the electric field, we
can control the valley degeneracy. As a function of $E_z$, Hall plateaux appear
at the filling factors $\nu =0,\pm 1,\pm 2,\pm 3,...$ except for the points
where level crossings occur.

View original: http://arxiv.org/abs/1202.1357