758 research outputs found
Observation of Zeeman effect in topological surface state with distinct material dependence
The helical Dirac fermions on the surface of topological insulators host
novel relativistic quantum phenomena in solids. Manipulating spins of
topological surface state (TSS) represents an essential step towards exploring
the theoretically predicted exotic states related to time reversal symmetry
(TRS) breaking via magnetism or magnetic field. Understanding Zeeman effect of
TSS and determining its g-factor are pivotal for such manipulations in the
latter form of TRS breaking. Here, we report those direct experimental
observations in Bi2Se3 and Sb2Te2Se by spectroscopic imaging scanning tunneling
microscopy. The Zeeman shifting of zero mode Landau level is identified
unambiguously by judiciously excluding the extrinsic influences associated with
the non-linearity in the TSS band dispersion and the spatially varying
potential. The g-factors of TSS in Bi2Se3 and Sb2Te2Se are determined to be 18
and -6, respectively. This remarkable material dependence opens a new route to
control the spins in the TSS.Comment: main text: 17 pages, 4 figures; supplementary: 15 pages, 7 figure
The effect of an imaginary part of the Schwinger-Dyson equation at finite temperature and density
We examined the effect of an imaginary part of the ladder approximation
Schwinger-Dyson equation. We show the imaginary part enhances the effect of the
first order transition, and affects a tricritical point. In particular, a
chemical potential at a tricritical point is moved about 200(MeV). Thus, one
should not ignore the imaginary part. On the other hand, since an imaginary
part is small away from a tricritical point, one should be able to ignore an
imaginary part. In addition, we also examined the contribution of the wave
function renormalization constant.Comment: 12 pages, 14 figure
Low-Energy Surface States in the Normal State of -PdBi2 Superconductor
Topological superconductors as characterized by Majorana surface states has
been actively searched for their significance in fundamental science and
technological implication. The large spin-orbit coupling in Bi-Pd binaries has
stimulated extensive investigations on the topological surface states in these
superconducting compounds. Here we report a study of normal-state electronic
structure in a centrosymmetric -PdBi2 within density functional theory
calculations. By investigating the electronic structure from the bulk to slab
geometries in this system, we predict for the first time that -PdBi2
can host orbital-dependent and asymmetric Rashba surface states near the Fermi
energy. This study suggests that -PdBi2 will be a good candidate to
explore the relationship between superconductivity and topology in condensed
matter physics
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