67 research outputs found
Experimental Electronic Structure and Interband Nesting in BaVS_3
The correlated 3d sulphide BaVS_3 is a most interesting compound because of
the apparent coexistence of one-dimensional and three-dimensional properties.
Our experiments explain this puzzle and shed new light on its electronic
structure. High-resolution angle-resolved photoemission measurements in a 4eV
wide range below the Fermi level explored the coexistence of weakly correlated
a_1g wide-band and strongly correlated e_g narrow-band d-electrons that is
responsible for the complicated behavior of this material. The most relevant
result is the evidence for a_1g--e_g inter-band nesting condition.Comment: 4 pages, 3 figure
A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
When electrons are subject to a large external magnetic field, the
conventional charge quantum Hall effect \cite{Klitzing,Tsui} dictates that an
electronic excitation gap is generated in the sample bulk, but metallic
conduction is permitted at the boundary. Recent theoretical models suggest that
certain bulk insulators with large spin-orbit interactions may also naturally
support conducting topological boundary states in the extreme quantum limit,
which opens up the possibility for studying unusual quantum Hall-like phenomena
in zero external magnetic field. Bulk BiSb single crystals are
expected to be prime candidates for one such unusual Hall phase of matter known
as the topological insulator. The hallmark of a topological insulator is the
existence of metallic surface states that are higher dimensional analogues of
the edge states that characterize a spin Hall insulator. In addition to its
interesting boundary states, the bulk of BiSb is predicted to
exhibit three-dimensional Dirac particles, another topic of heightened current
interest. Here, using incident-photon-energy-modulated (IPEM-ARPES), we report
the first direct observation of massive Dirac particles in the bulk of
BiSb, locate the Kramers' points at the sample's boundary and
provide a comprehensive mapping of the topological Dirac insulator's gapless
surface modes. These findings taken together suggest that the observed surface
state on the boundary of the bulk insulator is a realization of the much sought
exotic "topological metal". They also suggest that this material has potential
application in developing next-generation quantum computing devices.Comment: 16 pages, 3 Figures. Submitted to NATURE on 25th November(2007
Soluble FGL2, a novel effector molecule of activated hepatic stellate cells, regulates T-cell function in cirrhotic patients with hepatocellular carcinoma
Hochst Oral History Transcript
Transcript of an oral history with Hartmut Hochst, scientific director, of the Synchrotron Radiation Center. Conducted by Eric Verbeten
Hochst Oral History
Oral history with Hartmut Hochst, scientific director, of the Synchrotron Radiation Center. Conducted by Eric Verbeten
Mobile small polarons and the Peierls transition in the quasi-one-dimensional conductor K0.3MoO3
High-resolution angle-resolved photoemission spectroscopy (ARPES) on the quasi-one-dimensional Peierls system K0.3MoO3 reveals a "hidden" open Fermi surface and band features displaying the symmetry properties of the underlying lattice. However, the ARPES line shapes and optical data suggest that the corresponding quasiparticles are heavily renormalized by strong electron-phonon interactions. The temperature dependence of the leading edge of the mostly incoherent spectrum bears signatures of the Peierls transition at T-P=180 K and of pretransitional fluctuations
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