2,652 research outputs found
Probing crossover from analogous weak antilocalization to localization by an Aharonov-Bohm interferometer on topological insulator surface
We propose a scanning tunneling microscopy Aharonov-Bohm (AB) interferometer
on the surface of a topological insulator (TI) to probe the crossover from
analogous weak antilocalization (WAL) to weak localization (WL) phenomenon via
the AB oscillations in spin-resolved local density of states (LDOS). Based on
our analytical and numerical results, we show that with increasing the energy
gap of TI surface states, the = periodic AB oscillations in
spin-resolved LDOS gradually transit into the periodic oscillations.Comment: 4.2 APL pages, 2 figure
Aharonov-Bohm oscillations in the local density of topological surface states
We study Aharonov-Bohm (AB) oscillations in the local density of states
(LDOS) for topological insulator (TI) and conventional metal Au(111) surfaces
with spin-orbit interaction, which can be probed by spin-polarized scanning
tunneling microscopy. We show that the spacial AB oscillatory period in the
total LDOS is a flux quantum (weak localization) in
both systems. Remarkably, an analogous weak antilocalization with
periodic spacial AB oscillations in spin components of LDOS for TI surface is
observed, while it is absent in Au(111).Comment: 4 APL pages, 3 figure
Quantum Corrals and Quantum Mirages on the Surface of a Topological Insulator
We study quantum corrals on the surface of a topological insulator (TI).
Different resonance states induced by nonmagnetic (NM), antiferromagnetic
(AFM), and ferromagnetic (FM) corrals are found. Intriguingly, the spin is
clearly energy-resolved in a FM corral, which can be effectively used to
operate surface carrier spins of TI. We also show that an observable quantum
mirage of a magnetic impurity can be projected from the occupied into the empty
focus of a FM elliptic corral, while in NM and AFM corrals the mirage signal
becomes negligibly weak. In addition, the modulation of the interaction between
two magnetic impurities in the quantum corrals is demonstrated. These prominent
effects may be measured by spin-polarized STM experiments.Comment: 5 PRB pages, 4 figure
On Finite Time Singularity and Global Regularity of an Axisymmetric Model for the 3D Euler Equations
We investigate the large time behavior of an axisymmetric model for the 3D
Euler equations. In \cite{HL09}, Hou and Lei proposed a 3D model for the
axisymmetric incompressible Euler and Navier-Stokes equations with swirl. This
model shares many properties of the 3D incompressible Euler and Navier-Stokes
equations. The main difference between the 3D model of Hou and Lei and the
reformulated 3D Euler and Navier-Stokes equations is that the convection term
is neglected in the 3D model. In \cite{HSW09}, the authors proved that the 3D
inviscid model can develop a finite time singularity starting from smooth
initial data on a rectangular domain. A global well-posedness result was also
proved for a class of smooth initial data under some smallness condition. The
analysis in \cite{HSW09} does not apply to the case when the domain is
axisymmetric and unbounded in the radial direction. In this paper, we prove
that the 3D inviscid model with an appropriate Neumann-Robin boundary condition
will develop a finite time singularity starting from smooth initial data in an
axisymmetric domain. Moreover, we prove that the 3D inviscid model has globally
smooth solutions for a class of large smooth initial data with some appropriate
boundary condition.Comment: Please read the published versio
Multiple scattering theory of quasiparticles on a topological insulator surface
A general partial-wave multiple scattering theory for scattering from
cylindrically symmetric potentials on a topological insulator (TI) surface is
developed. As an application, the cross sections for a single scatterer and two
scatterers are discussed. We find that the symmetry of differential cross
section is reduced and the backscattering is allowed for massive Dirac fermions
on gapped TI surface. Remarkably, a sharp resonance peak at the band edge of
the gapped TI is found in the total cross section , which may
offer a useful way to determine the gap (as well as the effective mass of
quasiparticles) on TI surface. We show that the interference effect is obvious
in cross sections during the quasiparticle scattering between the scatterer
pair, and additional resonance peaks are introduced in when the
higher partial waves are taken into account.Comment: 10 pages, 3 figure
Quasiparticle states and quantum interference induce by magnetic impurities on a two-dimensional topological superconductor
We theoretically study the effect of localized magnetic impurities on
two-dimensional topological superconductor (TSC). We show that the local
density of states (LDOS) can be tuned by the effective exchange field , the
chemical potential of TSC, and the distance as well as
relative spin angle between two impurities. The changes in
between two impurities alter the interference and result in significant
modifications to the bonding and antibonding states. Furthermore, the
bound-state spin LDOS induced by single and double magnetic impurity
scattering, the quantum corrals, and the quantum mirages are also discussed.
Finally, we briefly compare the impurities in TSC with those in topological
insulators.Comment: J. Phys.: Condens. Matter 24, 145502 (2012
A Bionic Fish Cilia Median-Low Frequency Three-Dimensional Piezoresistive MEMS Vector Hydrophone
Analysis of Affinely Equivalent Boolean Functions
By walsh
transform, autocorrelation function, decomposition, derivation and
modification of truth table, some new invariants are obtained.
Based on invariant theory, we get two results: first a general
algorithm which can be used to judge if two boolean functions are
affinely equivalent and to obtain the affine equivalence
relationship if they are equivalent. For example, all 8-variable
homogenous bent functions of degree 3 are classified into 2
classes; second, the classification of the Reed-Muller code
which can be used to almost
enumeration of 8-variable bent functions
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