5,122 research outputs found
Fully gapped superconducting state in Au2Pb: a natural candidate for topological superconductor
We measured the ultra-low-temperature specific heat and thermal conductivity
of AuPb single crystal, a possible three-dimensional Dirac semimetal with a
superconducting transition temperature 1.05 K. The electronic
specific heat can be fitted by a two-band s-wave model, which gives the gap
amplitudes (0)/ = 1.38 and (0)/ = 5.25.
From the thermal conductivity measurements, a negligible residual linear term
in zero field and a slow field dependence of at low
field are obtained. These results suggest that AuPb has a fully gapped
superconducting state in the bulk, which is a necessary condition for
topological superconductor if AuPb is indeed one.Comment: 6 pages, 4 figure
Spatial memory impairment by TRPC1 depletion is ameliorated by environmental enrichment
published_or_final_versio
An improvement of isochronous mass spectrometry: Velocity measurements using two time-of-flight detectors
Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for
mass measurements of exotic nuclei with very short half-lives down to several
tens of microseconds, using a multicomponent secondary beam separated in-flight
without cooling. However, the inevitable momentum spread of secondary ions
limits the precision of nuclear masses determined by using IMS. Therefore, the
momentum measurement in addition to the revolution period of stored ions is
crucial to reduce the influence of the momentum spread on the standard
deviation of the revolution period, which would lead to a much improved mass
resolving power of IMS. One of the proposals to upgrade IMS is that the
velocity of secondary ions could be directly measured by using two
time-of-flight (double TOF) detectors installed in a straight section of a
storage ring. In this paper, we outline the principle of IMS with double TOF
detectors and the method to correct the momentum spread of stored ions.Comment: Accepted by Nuclear Inst. and Methods in Physics Research,
Enhanced electron correlations in the new binary stannide PdSn4: a homologue of the Dirac nodal arc semimetal PtSn4
The advent of nodal-line semi-metals, i.e. systems in which the conduction
and valence bands cross each other along a closed trajectory (line or loop)
inside the Brillouin zone, has opened up a new arena for the exploration of
topological condensed matter in which, due to a vanishing density of states
near the Fermi level, electron correlation effects may also play an important
role. In spite of this conceptual richness however, material realization of
nodal-line (loop) fermions is rare, with PbTaSe2, ZrSiS and PtSn4 the only
promising known candidates. Here we report the synthesis and physical
properties of a new compound PdSn4 that is isostructural with PtSn4 yet
possesses quasiparticles with significantly enhanced effective masses. In
addition, PdSn4 displays an unusual polar angular magnetoresistance which at a
certain field orientation, varies linearly with field up to 55 Tesla. Our study
suggests that, in association with its homologue PtSn4 whose low-lying
excitations were recently claimed to possess Dirac node arcs, PdSn4 may be a
promising candidate in the search for novel topological states with enhanced
correlation effects.Comment: 6 figures, 1 tabl
Extraordinary quasiparticle scattering and bandwidth-control by dopants in iron-based superconductors
The diversities in crystal structures and ways of doping result in extremely
diversified phase diagrams for iron-based superconductors. With angle-resolved
photoemission spectroscopy (ARPES), we have systematically studied the effects
of chemical substitution on the electronic structure of various series of
iron-based superconductors. In addition to the control of Fermi surface
topology by heterovalent doping, we found two more extraordinary effects of
doping: 1. the site and band dependencies of quasiparticle scattering; and more
importantly 2. the ubiquitous and significant bandwidth-control by both
isovalent and heterovalent dopants in the iron-anion layer. Moreover, we found
that the bandwidth-control could be achieved by either applying the chemical
pressure or doping electrons, but not by doping holes. Together with other
findings provided here, these results complete the microscopic picture of the
electronic effects of dopants, which facilitates a unified understanding of the
diversified phase diagrams and resolutions to many open issues of various
iron-based superconductors.Comment: 12 pages, 9 figure
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