Collective excitations on a surface of topological insulator
نویسندگان
چکیده
We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particles and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We develop quantum field-theoretical description of spin-plasmons in helical liquid and study their properties and internal structure. Value of spin polarization arising in the system with excited spin-plasmons is calculated. We also consider the scattering of spin-plasmons on magnetic and nonmagnetic impurities and external potentials, and show that the scattering occurs mainly into two side lobes. Analogies with Dirac electron gas in graphene are discussed.PACS: 73.20.Mf; 73.22.Lp; 75.25.Dk.
منابع مشابه
Chiral Spin Mode on the Surface of a Topological Insulator.
Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi_{2}Se_{3}. We observe a sharp peak at 150 meV in the pseudovector A_{2} symmetry channel of the Raman spectra. By comparing the data with calculations, we identify this peak as the transverse collective spin mode of surface...
متن کاملExceptional surface and bulk electronic structures in a topological insulator, Bi2Se3
The outstanding problem in topological insulators is the bulk metallicity underneath topologically ordered surface states and the appearance of Dirac point far away from the Fermi energy. Enormous efforts are being devoted to get the Dirac point at the Fermi level via exposure to foreign materials so that these materials can be used in technology and realize novel fundamental physics. Ironicall...
متن کاملSpin-charge separation of plasmonic excitations in thin topological insulators
We discuss plasmonic excitations in a thin slab of topological insulators. In the limit of no hybridization of the surface states and same electronic density of the two layers, the electrostatic coupling between the top and bottom layers leads to optical and acoustic plasmons which are purely charge and spin collective oscillations. We then argue that a recent experiment on the plasmonic excita...
متن کاملVacuum-ultraviolet plasma Frenkel excitons: elementary excitations of polymerized fullerene
The high-frequency excitations of the molecular insulator C60 are investigated theoretically. The model of a quantum well rolled into a sphere is used to calculate the dipole ~multipole in the general case! modes of an individual C60 cluster. If the spectrum and oscillator strengths of the collective modes of an individual cluster are known, the microscopic continuum approach can be used to cal...
متن کاملLocalized surface plasmon enhanced photothermal conversion in Bi2Se3 topological insulator nanoflowers
Localized surface plasmons (LSP), the confined collective excitations of electrons in noble metal and doped semiconductor nanostructures, enhance greatly local electric field near the surface of the nanostructures and result in strong optical response. LSPs of ordinary massive electrons have been investigated for a long time and were used as basic ingredient of plasmonics and metamaterials. LSP...
متن کامل