231 research outputs found
Observation of two species of vortices in the anisotropic spin-triplet superconductor
Magnetic flux structures in single crystals of the layered spin triplet
superconductor SrRuO are studied by scanning micro SQUID Force
microscopy. Vortex chains appear as the applied field is tilted along the
in-plane direction of the superconductor. The vortex chains align along the
direction of the in-plane component of the applied magnetic field. The
decoration of in-plane vortices by crossing Abrikosov vortices is observed: two
vortex orientations are apparent simultaneously, one along the layers and the
other perpendicular to the layers. The crossing vortices appear preferentially
on the in-plane vortices
Observation of vortex coalescence in the anisotropic spin-triplet superconductor SrRuO
We present direct imaging of magnetic flux structures in the anisotropic,
spin-triplet superconductor SrRuO using a scanning SQUID
microscope. Individual quantized vortices were seen at low magnetic fields.
Coalescing vortices forming flux domains were revealed at intermediate fields.
Based on our observations we suggest that a mechanism intrinsic to the material
stabilizes the flux domains against the repulsive vortex-vortex interaction.
Topological defects like domain walls can provide this, implying proof for
unconventional chiral superconductivity.Comment: submitted to PR
Decoherence of electron beams by electromagnetic field fluctuations
Electromagnetic field fluctuations are responsible for the destruction of
electron coherence (dephasing) in solids and in vacuum electron beam
interference. The vacuum fluctuations are modified by conductors and
dielectrics, as in the Casimir effect, and hence, bodies in the vicinity of the
beams can influence the beam coherence. We calculate the quenching of
interference of two beams moving in vacuum parallel to a thick plate with
permittivity . In case of an
ideal conductor or dielectric the dephasing is suppressed
when the beams are close to the surface of the plate, because the random
tangential electric field , responsible for dephasing, is zero at the
surface. The situation is changed dramatically when
or are finite. In this case there exists a layer near
the surface, where the fluctuations of are strong due to evanescent
near fields. The thickness of this near - field layer is of the order of the
wavelength in the dielectric or the skin depth in the conductor, corresponding
to a frequency which is the inverse electron time of flight from the emitter to
the detector. When the beams are within this layer their dephasing is enhanced
and for slow enough electrons can be even stronger than far from the surface
Concept of an ionizing time-domain matter-wave interferometer
We discuss the concept of an all-optical and ionizing matter-wave
interferometer in the time domain. The proposed setup aims at testing the wave
nature of highly massive clusters and molecules, and it will enable new
precision experiments with a broad class of atoms, using the same laser system.
The propagating particles are illuminated by three pulses of a standing
ultraviolet laser beam, which detaches an electron via efficient single
photon-absorption. Optical gratings may have periods as small as 80 nm, leading
to wide diffraction angles for cold atoms and to compact setups even for very
massive clusters. Accounting for the coherent and the incoherent parts of the
particle-light interaction, we show that the combined effect of phase and
amplitude modulation of the matter waves gives rise to a Talbot-Lau-like
interference effect with a characteristic dependence on the pulse delay time.Comment: 25 pages, 5 figure
Magnetic state in URu2Si2, UPd2Al3 and UNi2Al3 probed by point contacts
The antiferromagnetic (AFM) state has been investigated in the three
heavy-fermion compounds URu2Si2, UPd2Al3, and UNi2Al3 by measuring dV/dI(V)
curves of point contacts at different temperatures (1.5-20 K) and magnetic
fields (0-28 T). The zero-bias maximum in dV/dI(V) for URu2Si2 points to a
partially gapped Fermi-surface related to the itinerant nature of the AFM state
contrary to UPd2Al3 where analogous features have not been found. The AFM state
in UNi2Al3 has more similarities with URu2Si2. For URu2Si2, the same critical
field of about 40 T along the easy c axis is found for all features in dV/dI(V)
corresponding to the Neel temperature, the gap in the electronic density of
states, and presumably the ordered moments.Comment: 10 pages incl. 5 figures, LaTex 2
Phase diagram of UPt in the model
The phase diagram of the unconventional superconductor UPt is explained
under the long-standing hypothesis that the pair wavefunction belongs to the
representation of the point group. The main objection to this theory
has been that it disagrees with the experimental phase diagram when a field is
applied along the c-axis. By a careful analysis of the free energy this
objection is shown to be incorrect. This singlet theory also explains the
unusual anisotropy in the upper critical field curves, often thought to
indicate a triplet pair function.Comment: 11 pages, Revtex, 2 figures (uuencoded, gzip'ed Postscript
The Sagnac Phase Shift suggested by the Aharonov-Bohm effect for relativistic matter beams
The phase shift due to the Sagnac Effect, for relativistic matter beams
counter-propagating in a rotating interferometer, is deduced on the bases of a
a formal analogy with the the Aharonov-Bohm effect. A procedure outlined by
Sakurai, in which non relativistic quantum mechanics and newtonian physics
appear together with some intrinsically relativistic elements, is generalized
to a fully relativistic context, using the Cattaneo's splitting technique. This
approach leads to an exact derivation, in a self-consistently relativistic way,
of the Sagnac effect. Sakurai's result is recovered in the first order
approximation.Comment: 18 pages, LaTeX, 2 EPS figures. To appear in General Relativity and
Gravitatio
Polymorphisms of Homologous Recombination Genes and Clinical Outcomes of Non-Small Cell Lung Cancer Patients Treated with Definitive Radiotherapy
The repair of DNA double-strand breaks (DSBs) is the major mechanism to maintain genomic stability in response to irradiation. We hypothesized that genetic polymorphisms in DSB repair genes may affect clinical outcomes among non-small cell lung cancer (NSCLC) patients treated with definitive radio(chemo)therapy. We genotyped six potentially functional single nucleotide polymorphisms (SNPs) (i.e., RAD51 −135G>C/rs1801320 and −172G>T/rs1801321, XRCC2 4234G>C/rs3218384 and R188H/rs3218536 G>A, XRCC3 T241M/rs861539 and NBN E185Q/rs1805794) and estimated their associations with overall survival (OS) and radiation pneumonitis (RP) in 228 NSCLC patients. We found a predictive role of RAD51 −135G>C SNP in RP development (adjusted hazard ratio [HR] = 0.52, 95% confidence interval [CI], 0.31–0.86, P = 0.010 for CG/CC vs. GG). We also found that RAD51 −135G>C and XRCC2 R188H SNPs were independent prognostic factors for overall survival (adjusted HR = 1.70, 95% CI, 1.14–2.62, P = 0.009 for CG/CC vs. GG; and adjusted HR = 1.70; 95% CI, 1.02–2.85, P = 0.043 for AG vs. GG, respectively) and that the SNP-survival association was most pronounced in the presence of RP. Our study suggests that HR genetic polymorphisms, particularly RAD51 −135G>C, may influence overall survival and radiation pneumonitis in NSCLC patients treated with definitive radio(chemo)therapy. Large studies are needed to confirm our findings
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