72 research outputs found
Non-trivial Surface-band Dispersion on Bi(111)
We performed angle-resolved photoelectron spectroscopy of the Bi(111) surface
to demonstrate that this surface support edge states of non-trivial topology.
Along the -direction of the surface Brillouin zone, a
surface-state band disperses from the projected bulk valence bands at
to the conduction bands at continuously, indicating
the non-trivial topological order of three-dimensional Bi bands. We ascribe
this finding to the absence of band inversion at the point of the bulk Bi
Brillouin zone. According to our analysis, a modification of tight-binding
parameters can account for the non-trivial band structure of Bi without any
other significant change on other physical properties.Comment: 13 pages, 4 figures. This manuscript has been accepted in New Journal
of Physic
Topological surface states of strained Mercury-Telluride probed by ARPES
The topological surface states of strained HgTe have been measured using
high-resolution ARPES measurements. The dispersion of surface states form a
Dirac cone, which origin is close to the top of the \ghh band: the top half of
the Dirac cone is inside the stress-gap while the bottom half lies within the
heavy hole bands and keeps a linear dispersion all the way to the X-point. The
circular dichroism of the photo-emitted electron intensity has also been
measured for all the bands.Comment: with supplementary materia
Effects of finite-range interactions on the one-electron spectral properties of one-dimensional metals: Application to Bi/InSb(001)
We study the one-electron spectral properties of one-dimensional interacting electron systems in which the interactions have finite range. We employ a mobile quantum impurity scheme that describes the interactions of the fractionalized excitations at energies above the standard Tomonga-Luttinger liquid limit and show that the phase shifts induced by the impurity describe universal properties of the one-particle spectral function. We find the explicit forms in terms of these phase shifts for the momentum dependent exponents that control the behavior of the spectral function near and at the (k,ω)-plane singularities where most of the spectral weight is located. The universality arises because the line shape near the singularities is independent of the short-distance part of the interaction potentials. For the class of potentials considered here, the charge fractionalized particles have screened Coulomb interactions that decay with a power-law exponent l>5. We apply the theory to the angle-resolved photo-electron spectroscopy (ARPES) in the highly one-dimensional bismuth-induced anisotropic structure on indium antimonide Bi/InSb(001). Our theoretical predictions agree quantitatively with both (i) the experimental value found in Bi/InSb(001) for the exponent α that controls the suppression of the density of states at very small excitation energy ω and (ii) the location in the (k,ω) plane of the experimentally observed high-energy peaks in the ARPES momentum and energy distributions. We conclude with a discussion of experimental properties beyond the range of our present theoretical framework and further open questions regarding the one-electron spectral properties of Bi/InSb(001).MIT - Massachusetts Institute of Technology(PTDC/FIS-MAC/29291/2017
Fluctuated spin-orbital texture of Rashba-split surface states in real and reciprocal space
Spin-orbit interaction (SOI) in low-dimensional systems, namely Rashba
systems and the edge states of topological materials, is extensively studied in
this decade as a promising source to realize various fascinating spintronic
phenomena, such as the source of the spin current and spin-mediated energy
conversion. Here, we show the odd fluctuation in the spin-orbital texture in a
surface Rashba system on Bi/InAs(110)-(21) by spin- and angle-resolved
photoelectron spectroscopy and a numerical simulation based on a
density-functional theory (DFT) calculation. The surface state shows a paired
parabolic dispersion with the spin degeneracy lifted by the Rashba effect.
Although its spin polarization should be fixed in a particular direction based
on the Rashba model, the observed spin polarization varies greatly and even
reverses its sign depending on the wavenumber. DFT calculations also reveal
that the spin directions of two inequivalent Bi chains on the surface change
from nearly parallel (canted-parallel) to anti-parallel in real space in the
corresponding wavevector region. These results point out an oversimplification
of the nature of spin in Rashba and Dirac systems and provide more freedom than
expected for spin manipulation of photoelectrons.Comment: 23 pages, 7 figure
PcpA, which is involved in the degradation of pentachlorophenol in Sphingomonas chlorophenolica ATCC39723, is a novel type of ring-cleavage dioxygenase
AbstractThe pentachlorophenol (PCP) mineralizing bacterium Sphingomonas chlorophenolica ATCC39723 degrades PCP via 2,6-dichlorohydroquinone (2,6-DCHQ). The pathway converting PCP to 2,6-DCHQ has been established previously; however, the pathway beyond 2,6-DCHQ is not clear, although it has been suggested that a PcpA plays a role in 2,6-DCHQ conversion. In this study, PcpA expressed in Escherichia coli was purified to homogeneity and shown to have novel ring-cleavage dioxygenase activity in conjunction with hydroquinone derivatives, and converting 2,6-DCHQ to 2-chloromaleylacetate
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