Propagation of Phonon in a Curved Space Induced by Strain Fields Instantons

We show that for a \textbf{multiple-connected} space the low energy strain fields excitations are given by instantons. Dirac fermions with a chiral mass and a pairing field propagates effectively in a multiple conected space. When the elastic strain field response is probed one finds that it is given by the \textbf{Pointriagin} characteristic. As a result the space time metric is modified. Applying an external stress field we observe that the phonon path bends in the transverse direction to the initial direction

A green's function approach for surface state photoelectrons in topological insulators

The topology of the surface electronic states is detected with photoemission. We explain the photoemission from the topological surface state . This is done by identifying the effective coupling between surface electrons-photons and vacuum electrons. The effective electron photon coupling is given by $e\tau^2$ where $\tau$ is the dimensionless tunneling amplitude of the zero mode surface states to tunnel into the vacuum. We compute the polarization and intensity of the emitted photoelectrons. We introduce a model which takes in account the Dirac Hamiltonian for the surface electron to photons coupling and the tunneling of the zero mode into the vacuum. Within the Green's function formalism we obtain exact results for the emitted Photoelectrons to second order in the laser field. The number of the emitted photoelectrons is sensitive to the laser coherent state intensity, the polarization is sensitive to the surface topology of the electronic states and the incoming photon polarization. The calculation is performed for the helical, Zeeman and warping case allowing to study spin textures.Comment: arXiv admin note: text overlap with arXiv:1501.0656

A microscopic model for detecting the surface states photoelectrons in Topological Insulators

We present a model for the photoelectrons emitted from the surface of a Topological insulator induced by a polarized laser source. The model is based on the tunneling of the surface electrons into the vacuum in the presence of a photon field. Using the Hamiltonian which describes the coupling of the photons to the surface electrons we compute the intensity and polarization of the photoelectrons

Tunnelling of Polarized Electrons in Magnetic Wires

We investigate the tunnelling between an electronic gas with two different velocities $V_\uparrow \neq V_\downarrow$ and a regular metal. We find that at the interface between the two systems that the tunnelling conductance for spin up and spin down are different. As a result a partly polarized gas (``magnetic wire'') is obtained. This result is caused by the e-e interaction, $g_2'' - g_1'' \neq 0$, which in the presence of $V_\uparrow \neq V_\downarrow$ gives rise to two different tunnelling exponents.Comment: 9 page

The Non-Dissipative Spin-Hall Current

A theory based on the Aharonov -Bohm effect in the momentum space for the Spin-Hall conductivity without a magnetic field is presented. The two dimensional Rashba Hamiltonian is diagonalized in the momentum spinor basis. This spinor is singular at K=0. The representation of the cartesian coordinates in the spinor momentum basis obey non-commutative rules. The non-commuting relations are a result of an effective Aharonov-Bohm vortex at K=0. We find the exact value of $\frac{e}{4\pi}$ for the Spin-Hall conductivity. The effect of a time reversal scattering potential on the Spin-Hall current causes the current to vanishes for an infinite system.Comment: submitted to P.R.

The Non-Dissipative Spin-Hall Conductivity and The Identification of the Conserved Current

The two dimensional Rashba Hamiltonian is investigated using the momentum representation.One finds that the SU(2) transformation which diagonalizes the Hamiltonian gives rise to non commuting Cartesian coordinates for K=0 and zero otherwise.This result corresponds to the Aharonov -Bohm phase in the momentum space. The Spin -Hall conductivity is given by $\frac{e}{4\pi}$ which disagree with the result $\frac{e}{8\pi}$ given in the literature.Using Stokes theorem we find that the Spin -Hall current is carried equally by the up and down electrons on the Fermi surface. We identify the Magnetic current and find that for an electric field with a finite Fourier component in the momentum space a non zero Spin -Hall current is obtained.For the electric field which is constant in space, the orbital magnetic current cancels the spin current. In order to measure the Spin-Hall conductance we propose to apply a magnetic field gradient $\Delta H_{2}$ in the $i=2$ direction and to measure a Charge- Hall current $\frac{e}{h}(\frac{g}{2})\mu_{B}\Delta H_{2}$ in the $i=1$ direction.Comment: 9 pages, 1 figure, submitted to PR

Electrodynamics effects in 3+1 dimensions induced by interactions in Topological Insulators

We investigate the effect of interactions in the Topological Insulator in 3+1 dimensions. We show that for a particular type of interactions, the Electrodynamics response is equivalent to the response of non-interacting Topological Insulator in 4+1 dimensions

Topological spin current

We present an exact derivation for non-commuting coordinates induced by the SU(2) transformation used to diagonalize the spin-orbit hamiltonian in two dimension.As a result an exact non-dissipative Hall current less sensitive to disorder and complementary to the dissipative conductivity is found. We compute the non-dissipative charge and spin-Hall conductance for the spin-orbit problem.We find that the spin-Hall conductance is quantized in units of $\frac{eg\mu_{B}}{h}$ .In the presence of a Zeeman interaction the charge-Hall conductivity is proportional to the magnetic field. We propose an experiment to test our theory

Proposal for the detection of Majorana Fermions in Topological Superconductors

One of the goals of modern spectroscopy is to invent techniques which detect neutral excitations that have been theoretically proposed. For superconductors, two point transport measurements detect the Andreev crossed reflection which confirms the existence of the Majorana fermions. Similar information can be obtained from a measurement using two piezoelectric transducers. One transducer measures the stress tensor response from the strain field generated by the second transducer. The ratio between the stress response and strain velocity determines the dissipative response. We will show that the dissipative stress response can be used for a Topological Superconductor. We will investigate a Topological Superconductor in a magnetic field, an Abrikosov vortex lattice with Majorana dispersive fermions is formed which is used to compute the dissipative stress response and identify the Majorana fermions and quasi-particles

The Marginal Fermi Liquid - An Exact Derivation Based on Dirac's First Class Constraints Method

Dirac's method for constraints is used for solving the problem of exclusion of double occupancy for Correlated Electrons. The constraints are enforced by the pair operator $Q(\vec{x})=\psi_{\downarrow}(\vec{x})\psi_{\uparrow}(\vec{x})$ which annihilates the ground state $|\Psi^0>$. Away from half fillings the operator $Q(\vec{x})$ is replaced by a set of $first$ $class$ Non-Abelian constraints $Q^{(-)}_{\alpha}(\vec{x})$ restricted to negative energies. The propagator for a single hole away from half fillings is determined by modified measure which is a function of the time duration of the hole propagator. As a result: a) The imaginary part of the self energy - is linear in the frequency. At large hole concentrations a Fermi Liquid self energy is obtained. b) For the Superconducting state the constraints generate an asymmetric spectrum excitations between electrons and holes giving rise to an asymmetry tunneling density of states.Comment: 33 pages, 5 figure