Authors: H.-H. Kung, S. Maiti, X. Wang, S.-W. Cheong, D.L. Maslov, G. Blumberg
Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, Bi2Se3. We observe a sharp peak at 150 meV in the pseudovector A2 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.
Our manuscript 'Surface vibrational modes of the topological insulator Bi2Se3 observed by Raman spectroscopy' is published online in Phys. Rev. B 95, 245406 (2017) (link; PDF), see more details here.
Our manuscript 'Superconductivity and electronic fluctuations in Ba1−xKxFe2As2 studied by Raman scattering' is published online in Phys. Rev. B 95, 085125 (2017) (link; PDF), see more details here.
Our manuscript 'Analogy Between the “Hidden Order” and the Orbital Antiferromagnetism in URu2−xFexSi2' is published online in Phys. Rev. Lett. (link), see more details here.