4,709 research outputs found
Observation of in-gap surface states in the Kondo insulator SmB6 by photoemission
Kondo insulators (KIs) are strongly correlated materials in which the
interactions between 4f and conduction electrons lead to a hybridization gap
opening at low temperature 1-2. SmB6 is a typical KI, but its resistivity does
not diverge at low temperatures, which was attributed to some in-gap states
3-10. However after several decades of research, the nature and origin of the
in-gap states remain unclear. Recent band calculation and transport
measurements suggest that the in-gap states could actually be ascribed to
topological surface states. SmB6 thus might be the first realization of
topological Kondo insulator (TKI) 13, the strongly correlated version of
topological insulator (TI) 11,12. Here by performing angle-resolved
photoemission spectroscopy (ARPES), we directly observed several dispersive
states within the hybridization gap of SmB6, which cross the Fermi level and
show negligible kz dependence, indicative of their surface origin. Furthermore,
the circular dichroism (CD) ARPES results of the in-gap states suggest the
chirality of orbital momentum, and temperature dependent measurements have
shown that the in-gap states vanish simultaneously with the hybridization gap
around 150 K. These strongly suggest their possible topological origin.Comment: 18 pages, 8 figure
Tumor initiating cells in Esophageal squamous cell carcinomas express high levels of CD44
10.1371/journal.pone.0021419PLoS ONE66
A side-by-side comparison of Daya Bay antineutrino detectors
The Daya Bay Reactor Neutrino Experiment is designed to determine precisely
the neutrino mixing angle with a sensitivity better than 0.01 in
the parameter sin at the 90% confidence level. To achieve this
goal, the collaboration will build eight functionally identical antineutrino
detectors. The first two detectors have been constructed, installed and
commissioned in Experimental Hall 1, with steady data-taking beginning
September 23, 2011. A comparison of the data collected over the subsequent
three months indicates that the detectors are functionally identical, and that
detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure
Observation of electron-antineutrino disappearance at Daya Bay
The Daya Bay Reactor Neutrino Experiment has measured a non-zero value for
the neutrino mixing angle with a significance of 5.2 standard
deviations. Antineutrinos from six 2.9 GW reactors were detected in
six antineutrino detectors deployed in two near (flux-weighted baseline 470 m
and 576 m) and one far (1648 m) underground experimental halls. With a 43,000
ton-GW_{\rm th}-day livetime exposure in 55 days, 10416 (80376) electron
antineutrino candidates were detected at the far hall (near halls). The ratio
of the observed to expected number of antineutrinos at the far hall is
. A rate-only analysis
finds in a
three-neutrino framework.Comment: 5 figures. Version to appear in Phys. Rev. Let
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