Chiral Spin Mode on the Surface of a Topological Insulator

Abstract

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 Dirac fermions. This mode, unlike a Dirac plasmon or a surface plasmon in the charge sector of excitations, is analogous to a spin wave in a partially polarized Fermi liquid, with spin-orbit coupling playing the role of an effective magnetic field.

arXiv comment9 pages, 7 figures, accepted for publication in Phys. Rev. Lett

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Cited by in corpus (23)

• A Chirality-Based Quantum Leap
• Tuning Inelastic Light Scattering via Symmetry Control in 2D Magnet CrI${}_3$
• Observation of Chiral Surface Excitons in a Topological Insulator Bi${}_2$Se${}_3$
• First-principles calculations of double resonance Raman spectra for monolayer MoTe${}_2$
• Collective spin modes in Fermi liquids with spin-orbit coupling
• Chirality and intrinsic dissipation of spin modes in two-dimensional electron liquids
• Raman Scattering as a Selective Probe of Chiral Electronic Excitations in Bilayer Graphene
• Electronic and Vibrational Excitations on the Surface of the Three-Dimensional Topological Insulator Bi${}_2$Te${}_{3-x}$Se${}_x$ (x = 0, 2, 3)
• Excitonic collective modes in Weyl semi-metals
• Spin-orbit interaction enabled electronic Raman scattering from charge collective modes
• Phase diagram of the interacting persistent spin-helix state
• Real-space nanoimaging of THz polaritons in the topological insulator Bi2Se3
• Dynamical spin-spin susceptibility of Silicene
• Phonon-Induced Collective Modes in Spin-Orbit Coupled Polar Metals
• Chiral Electronic Excitations in a Quasi-2D Rashba System BiTeI
• Spin waves in doped graphene: a time-dependent spin-density-functional approach to collective excitations in paramagnetic two-dimensional Dirac fermion gases
• Spin-Mediated Direct Photon Scattering by Plasmons in BiTeI
• Chiral electronic excitations and strong electron-phonon coupling to Weyl fermions in the Kagome semimetal Co${}_3$Sn${}_2$S${}_2$
• Dirac plasmon polaritons and magnetic modes in topological-insulator nanoparticles
• Resonant Edelstein and inverse-Edelstein effects, charge-to-spin conversion, and spin pumping from chiral-spin modes
• Many-body correction to the intrinsic anomalous and spin Hall conductivities
• Electronic Raman scattering from 2D metals with broken inversion symmetry
• Zero-field spin resonance in graphene with proximity-induced spin-orbit coupling