Time-dependent current density functional theory via time-dependent deformation functional theory: A constrained search formulation in the time domain

The logical structure and the basic theorems of time-dependent current density functional theory (TDCDFT) are analyzed and reconsidered from the point of view of recently proposed time-dependent deformation functional theory (TDDefFT). It is shown that the formalism of TDDefFT allows to avoid a traditional external potential-to-density/current mapping. Instead the theory is formulated in a form similar to the constrained search procedure in the ground state DFT. Within this formulation of TDCDFT all basic functionals appear from the solution of a constrained universal many-body problem in a comoving reference frame, which is equivalent to finding a conditional extremum of a certain universal action functional. As a result the physical origin of the universal functionals entering the theory, as well as their proper causal structure becomes obvious. In particular, this leaves no room for any doubt concerning predictive power of the theory.Comment: revtex4, 24 page

Orbital momentum Hall effect in p-doped graphane

It is shown that an electric field applied to p-doped graphane generates a dissipationless orbital momentum Hall current. In the clean limit the corresponding Hall conductivity is independent of the concentration of holes. The Hall effect is related to the $2\pi$-Berry phase accumulated when heavy and light holes are transported around the degeneracy point in the center of the Brillouin zone. This also leads to the orbital momentum edge currents in the equilibrium state, and to the accumulation of the orbital momentum at the edges when the system is driven out of equilibrium.Comment: RevTeX 4, 4 pages, 2 figures, final versio

Spin evolution of cold atomic gases in SU(2)⊗\otimes U(1) fields

We consider response function and spin evolution in spin-orbit coupled cold atomic gases in a synthetic gauge magnetic field influencing solely the orbital motion of atoms. We demonstrate that various regimes of spin-orbit coupling strength, magnetic field, and disorder can be treated within a single approach based on the representation of atomic motion in terms of auxiliary collective classical trajectories. Our approach allows for a unified description of fermionic and bosonic gases.Comment: 8 pages, 2 figure

Diffusive and precessional spin dynamics in a two-dimensional electron gas with disorder: a gauge theory view

We develop a gauge theory for diffusive and precessional spin dynamics in two-dimensional electron gas with disorder. Our approach reveals a direct connections between the absence of the equilibrium spin current and strong anisotropy in the spin relaxation: both effects arise if the spin-orbit coupling is reduced to a pure gauge SU(2) field. In this case, by a gauge transformation in the form of a local SU(2) rotation in the spin subspace the spin-orbit coupling can be removed. The resulting spin dynamics is exactly described in terms of two kinetic coefficients: the spin diffusion and electron mobility. After the inverse transformation, full diffusive and precessional spin density dynamics, including the anisotropic spin relaxation, formation of stable spin structures, and spin precession induced by a macroscopic current, is restored. Explicit solutions of the spin evolution equations are found for the initially uniform spin density and for stable nonuniform structures. Our analysis demonstrates a universal relation between the spin relaxation rate and spin diffusion coefficient.Comment: published version, minor correction