482 research outputs found
Detailed Topography of the Fermi Surface of Sr2RuO4
We apply a novel analysis of the field and angle dependence of the
quantum-oscillatory amplitudes in the unconventional superconductor Sr2RuO4 to
map its Fermi surface in unprecedented detail, and to obtain previously
inaccessible information on the band dispersion. The three quasi-2D Fermi
surface sheets not only exhibit very diverse magnitudes of warping, but also
entirely different dominant warping symmetries. We use the data to reassess
recent results on c-axis transport phenomena.Comment: REVTeX, 4 page
Double Giant Dipole Resonance in ^{208}Pb
Double-dipole excitations in ^{208}Pb are analyzed within a microscopic model
explicitly treating 2p2h-excitations. Collective states built from such
2p2h-excitations are shown to appear at about twice the energy of the isovector
giant dipole resonance, in agreement with the experimental findings. The
calculated cross section for Coulomb excitation at relativistic energies cannot
explain simultaneously the measured single-dipole and double-dipole cross
sections, however.Comment: 7 pages, Latex, 5 postscript figure
Single-crystal growth and dependences on the hole concentration and magnetic field of the magnetic ground state in the edge-sharing CuO chain system CaYCuO
We have succeeded in growing large-size single-crystals of
CaYCuO with and measured the
magnetic susceptibility, specific heat and magnetization curve, in order to
study the magnetic ground state in the edge-sharing CuO chain as a function
of hole concentration and magnetic field. In , it has been
found that an antiferromagnetically ordered phase with the magnetic easy axis
along the b-axis is stabilized and that a spin-flop transition occurs by the
application of magnetic fields parallel to the b-axis. The antiferromagnetic
transition temperature decreases with increasing and disappears around 1.4. Alternatively, a spin-glass phase appears around . At where the hole concentration is 1/3 per Cu, it appears that a
spin-gap state is formed owing to the formation of spin-singlet pairs. No sign
of the coexistence of an antiferromagnetically ordered state and a spin-gap one
suggested in CaCuO has been found in
CaYCuO.Comment: 13 pages, 12 figures, 1 tabl
Low temperature electronic properties of Sr_2RuO_4 III: Magnetic fields
Based on the microscopic model introduced previously the observed specific
heat and ac-susceptibility data in the superconducting phase in Sr_2RuO_4 with
applied magnetic fields are described consistently within a phenomenological
approach. Discussed in detail are the temperature dependence of the upper
critical fields H_{c2} and H_2, the dependence of the upper critical fields on
the field direction, the linear specific heat below the superconducting phase
transition as a function of field or temperature, the anisotropy of the two
spatial components of the order parameter, and the fluctuation field H_p.Comment: 8 pages REVTEX, 4 figure
Compatibility of QCD sum-rules and Hadron field theory in a dense medium
The compatibility of the QCD sum rules and effective hadronic models
predictions are examined. For this purpose we have considered the results for
the nucleon self-energy in a dense hadronic environment provided by two
independent QCD sum-rules calculations. They are immersed in a theory of
hadronic fields giving rise to non-linear interactions, whose vertices are
parameterized in different ways. Although all of them reproduce the self-energy
used as input, very different descriptions of nuclear observables are obtained.
Only under very definite circumstances we have found an acceptable agreement
with the nuclear matter properties. To achieve this, phenomenological
parameters are not required at all.Comment: 8 pages, 2 figure
Possible unconventional superconductivity in iron-based layered compound LaFePO: Study of heat capacity
Heat capacity measurements were performed on recently discovered iron based
layered superconductors, non doped LaFePO and fluorine doped LaFePO. A
relatively large electronic heat capacity coefficient and a small normalized
heat capacity jump at Tc = 3.3 K were observed in LaFePO. LaFePO0.94F0.06 had a
smaller electronic heat capacity coefficient and a larger normalized heat
capacity jump at Tc = 5.8 K. These values indicate that these compounds have
strong electron electron correlation and magnetic spin fluctuation, which are
the signatures of unconventional superconductivity mediated by spin
fluctuation.Comment: 15 Pages, 3 Figure
Thermo-magnetic hysteretic properties resembling superconductivity in the normal state of La1.85Sr0.15CuO4
We have performed detailed magnetic and thermal hysteresis experiments in the
normal-state magnetization of La1.85Sr0.15CuO4 single crystal. Using a
combination of in-field and in-zero-magnetic-field measurements at different
stages of thermal history of the sample, we identified subtle effects
associated with the presence of magnetic signatures which resemble those below
the superconducting transition temperature (Tc=36 K) but survive up to 250 K.Comment: One file including text and figure
The difference in congenital cholesteatoma CT findings based on the type of mass
AbstractObjectiveA retrospective assessment of differences in congenital cholesteatoma CT findings with a focus on type of cholesteatoma mass.Materials and methodsThe medical records and CT images of 14 patients with congenital cholesteatomas in the middle ear who underwent surgery at our institution between January 2009 and July 2014 were reviewed. Cholesteatomas were classified as closed type, open type, or mixed type based on intraoperative findings. The CT findings including cholesteatoma size, location, and shape were retrospectively reviewed.ResultsEight patients had closed type cholesteatomas, four had mixed type, and two had open type. The mean size of all cholesteatomas was 5.1mm. None of the cholesteatoma types indicated a tendency towards a certain location. The round shape was observed more frequently in closed type cholesteatomas than in other types (closed: 5/8; mixed: 1/4; open: 0/2). Two large closed type cholseteatomas and two mixed type cholesteatomas exhibited a constricted shape. Both of the open type cholesteatomas displayed an irregular shape.ConclusionSmall closed type congenital cholesteatomas were typically observed as round shaped lesions, but large closed type cholesteatomas and other type cholesteatomas tended to display shapes other than round
Field-angle Dependence of the Zero-Energy Density of States in the Unconventional Heavy-Fermion Superconductor CeCoIn5
Field-angle dependent specific heat measurement has been done on the
heavy-fermion superconductor CeCoIn5 down to ~ 0.29 K, in a magnetic field
rotating in the tetragonal c-plane. A clear fourfold angular oscillation is
observed in the specific heat with the minima (maxima) occurring along the
[100] ([110]) directions. Oscillation persists down to low fields H << Hc2,
thus directly proving the existence of gap nodes. The results indicate that the
superconducting gap symmetry is most probably of dxy type.Comment: 8 pages, 3 figures, to be published in J. Phys. Condens. Matte
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