32 research outputs found
Setting Boundaries with Memory: Generation of Topological Boundary States in Floquet-Induced Synthetic Crystals
When a d-dimensional quantum system is subjected to a periodic drive, it may
be treated as a (d+1)-dimensional system, where the extra dimension is a
synthetic one. In this work, we take these ideas to the next level by showing
that non-uniform potentials, and particularly edges, in the synthetic dimension
are created whenever the dynamics of system has a memory component. We
demonstrate that topological states appear on the edges of these synthetic
dimensions and can be used as a basis for a wave packet construction. Such
systems may act as an optical isolator which allows transmission of light in a
directional way. We supplement our ideas by an example of a physical system
that shows this type of physics.Comment: 7 Pages, 5 Figure
Magnetic Instability on the Surface of Topological Insulators
Gapless surface states that are protected by time reversal symmetry and
charge conservation are among the manifestations of 3D topological insulators.
In this work we study how electron-electron interaction may lead to spontaneous
breaking of time reversal symmetry on surfaces of such insulators. We find that
a critical interaction strength exists, above which the surface is unstable to
spontaneous formation of magnetization, and study the dependence of this
critical interaction strength on temperature and chemical potential.Comment: 4 pages, 3 figure
Current at a distance and resonant transparency in Weyl semimetals
Surface Fermi arcs are the most prominent manifestation of the topological
nature of Weyl semimetals. In the presence of a static magnetic field oriented
perpendicular to the sample surface, their existence leads to unique
inter-surface cyclotron orbits. We propose two experiments which directly probe
the Fermi arcs: a magnetic field dependent non-local DC voltage and sharp
resonances in the transmission of electromagnetic waves at frequencies
controlled by the field. We show that these experiments do not rely on quantum
mechanical phase coherence, which renders them far more robust and
experimentally accessible than quantum effects. We also comment on the
applicability of these ideas to Dirac semimetals.Comment: 10 pages, 8 figure
Nonlocal Coulomb drag in Weyl semimetals
Nonlocality is one of the most striking signatures of the topological nature of Weyl semimetals. We propose to probe the nonlocality in these materials via a measurement of a magnetic-field-dependent Coulomb drag between two sheets of graphene which are separated by a three-dimensional slab of Weyl semimetal. We predict a mechanism of Coulomb drag, based on cyclotron orbits that are split between opposite surfaces of the semimetal. In the absence of impurity scattering between different Weyl nodes, this mechanism does not decay with the thickness of the semimetal
Nonlocal Coulomb drag in Weyl semimetals
Nonlocality is one of the most striking signatures of the topological nature of Weyl semimetals. We propose to probe the nonlocality in these materials via a measurement of a magnetic-field-dependent Coulomb drag between two sheets of graphene which are separated by a three-dimensional slab of Weyl semimetal. We predict a mechanism of Coulomb drag, based on cyclotron orbits that are split between opposite surfaces of the semimetal. In the absence of impurity scattering between different Weyl nodes, this mechanism does not decay with the thickness of the semimetal
From Dynamical Localization to Bunching in interacting Floquet Systems
We show that a quantum many-body system may be controlled by means of Floquet
engineering, i.e., their properties may be controlled and manipulated by
employing periodic driving. We present a concrete driving scheme that allows
control over the nature of mobile units and the amount of diffusion in generic
many-body systems. We demonstrate these ideas for the Fermi-Hubbard model,
where the drive renders doubly occupied sites (doublons) the mobile excitations
in the system. In particular, we show that the amount of diffusion in the
system and the level of fermion-pairing may be controlled and understood solely
in terms of the doublon dynamics. We find that under certain circumstances the
diffusion in the system may be eliminated completely. We conclude our work by
generalizing these ideas to generic many-body systems.Comment: 10 pages, 5 figure
Density Waves Instability and a Skyrmion Lattice on the Surface of Strong Topological Insulators
In this work we analyze the instability conditions for spin-density-waves
(SDW) formation on the surface of strong topological insulators. We find that
for a certain range of Fermi-energies and strength of interactions the SDW
state is favored compared to the unmagnetized and the uniform-magnetization
states. We also find that the SDW are of spiral nature and for a certain range
of parameters a Skyrmion-lattice may form on the surface. We show that this
phase may have a non trivial Chern-number even in the absence of an external
magnetic field.Comment: 6 pages, 7 figure