E. J. Nicol

Valley-spin polarization in the magneto-optical response of silicene and other similar 2D crystals.

We calculate the magneto-optical conductivity and electronic density of states for silicene, the silicon equivalent of graphene, and similar crystals such as germanene. In the presence of a perpendicular magnetic field and electric field gating, we note that four spin- and valley-polarized levels can be seen in the density of states, and transitions between these levels lead to similarly polarized absorption lines in the longitudinal, transverse Hall, and circularly polarized dynamic conductivity. While previous spin and valley polarization predicted for the conductivity is only present in the response to circularly polarized light, we show that distinct spin and valley polarization can also be seen in the longitudinal magneto-optical conductivity at experimentally attainable energies. The frequency of the absorption lines may be tuned by the electric and magnetic field to onset in a range varying from THz to the infrared. This potential to isolate charge carriers of definite spin and valley label may make silicene a promising candidate for spin- and valleytronic devices.

ANISOTROPIC THERMODYNAMICS OF D-WAVE SUPERCONDUCTORS IN THE VORTEX STATE

We show that the density of states and the thermodynamic properties of a two-dimensional

Optical conductivity of bilayer graphene with and without an asymmetry gap

d

Properties of the superconducting state in a two-band model

-wave superconductor in the vortex state with applied magnetic field H in the plane depend on the angle between H and the order-parameter nodes. Within a semiclassical treatment of the extended quasiparticle states, we obtain fourfold oscillations of the specific heat, measurement of which provides a simple probe of gap symmetry. The frequency dependence of the density of states and the temperature dependence of thermodynamic properties obey different power laws for field in the nodal and antinodal direction. The fourfold pattern is changed to twofold when orthorhombicity is considered.

Magneto-Optical Conductivity of Silicene and Other Buckled Honeycomb Lattices

When a bilayer of graphene is placed in a suitably configured field effect device, an asymmetry gap can be generated and the carrier concentration made different in each layer. This provides a tunable semiconducting gap, and the valence and conductance bands no longer meet at the two Dirac points of the graphene Brillouin zone. We calculate the optical conductivity of such a semiconductor with particular emphasis on the optical spectral weight redistribution brought about by changes in gap and chemical potential due to charging. We derive an algebraic formula for an arbitrary value of the chemical potential for the case of the bilayer conductivity without a gap.

Optical signatures of the tunable band gap and valley-spin coupling in silicene

Eliashberg theory is used to investigate the range of thermodynamic properties possible within a two-band model for

AC/DC spin and valley Hall effects in silicene and germanene

s

Comparison of pressurized sulfur hydride with conventional superconductors

-wave superconductivity and to identify signatures of its two-band nature. We emphasize dimensionless BCS ratios [those for the energy gaps, the specific heat jump, and the negative of its slope near

Dynamical polarization function, plasmons, and screening in silicene and other buckled honeycomb lattices

{T}_{c}

Effect of electron-phonon interaction on spectroscopies in graphene

, the thermodynamic critical field