1,198 research outputs found
An energy scale directly related to superconductivity in the high- cuprate superconductors: Universality from the Fermi arc picture
We have performed a temperature dependent angle-resolved photoemission
spectroscopy (ARPES) study of the tri-layer high- cuprate superconductor
(HTSC) BiSrCaCuO (Bi2223), and have shown that
the \textquotedblleft effective\textquotedblright superconducting (SC) gap
defined at the end point of the Fermi arc and the (=
110 K) approximately satisfies the weak-coupling BCS-relationship
2 = 4.3. Combining this result with previous
ARPES results on single- and double-layer cuprates, we show that the
relationship between 2 = 4.3 holds for various
HTSCs. Furthermore, at , the quasi-patricle width at the end
point of the Fermi arc is found to coincide with , consistent
with the context of Planckian dissipation.Comment: 5 pages, 4 figure
Effect of electron-phonon coupling in the ARPES spectra of the tri-layer cuprate BiSrCaCuO
Angle-resolved photoemission spectroscopy using tunable low energy photons
allows us to study the quasi-particle (QP) dispersions of the inner and outer
CuO2 planes (IP and OP) separately in the tri-layer cuprate
BiSrCaCuO (Bi2223). The kink energy of the OP
band is 70 meV, as observed in various high- cuprates, while that
of the IP band is as large as 100 meV in the superconducting (SC) state. This
large kink energy is attributed to the 35 meV buckling mode plus the
large ( 60 meV) SC gap of IP. The IP band also shows a weak kink feature
at 70 meV in the SC state. The latter feature can be explained either by the 70
meV half-breathing mode or by the 35 meV buckling-phonon mode plus the
40 meV SC gap of OP if interlayer scattering of QP is involved.Comment: 5 pages, 2 figure
Orbital Degeneracy and Peierls Instability in Triangular Lattice Superconductor IrPtTe
We have studied electronic structure of triangular lattice
IrPtTe superconductor using photoemission spectroscopy and
model calculations. Ir core-level photoemission spectra show that Ir
charge modulation established in the low temperature phase of IrTe
is suppressed by Pt doping. This observation indicates that the suppression of
charge modulation is related to the emergence of superconductivity.
Valence-band photoemission spectra of IrTe suggest that the Ir charge
modulation is accompanied by Ir orbital reconstruction. Based on the
photoemission results and model calculations, we argue that the
orbitally-induced Peierls effect governs the charge and orbital instability in
the IrPtTe.Comment: 5 pages,4 figure
Electronic structure reconstruction by orbital symmetry breaking in IrTe2
We report an angle-resolved photoemission spectroscopy (ARPES) study on IrTe2
which exhibits an interesting lattice distortion below 270 K and becomes
triangular lattice superconductors by suppressing the distortion via chemical
substitution or intercalation. ARPES results at 300 K show multi-band Fermi
surfaces with six-fold symmetry which are basically consistent with band
structure calculations. At 20 K in the distorted phase, whereas the flower
shape of the outermost Fermi surface does not change from that at 300 K,
topology of the inner Fermi surfaces is strongly modified by the lattice
distortion. The Fermi surface reconstruction by the distortion depends on the
orbital character of the Fermi surfaces, suggesting importance of Ir 5d and/or
Te 5p orbital symmetry breaking.Comment: 4pages, 4figure
Significance of myocardial tenascin-C expression in left ventricular remodelling and long-term outcome in patients with dilated cardiomyopathy
Aim Dilated cardiomyopathy (DCM) has a variety of causes, and no useful approach to predict left ventricular (LV) remodelling and long-term outcome has yet been established. Myocardial tenascin-C (TNC) is known to appear under pathological conditions, possibly to regulate cardiac remodelling. The aim of this study was to clarify the significance of myocardial TNC expression in LV remodelling and the long-term outcome in DCM. Methods and results One hundred and twenty-three consecutive DCM patients who underwent endomyocardial biopsy for initial diagnosis were studied. Expression of TNC in biopsy sections was analysed immunohistochemically to quantify the ratio of the TNC-positive area to the whole myocardial tissue area (TNC area). Clinical parameters associated with TNC area were investigated. The patients were divided into two groups based on receiver operating characteristic analysis of TNC area to predict death: high TNC group with TNC area ≥2.3% (22 patients) and low TNC group with TNC area <2.3% (101 patients). High TNC was associated with diabetes mellitus. Comparing echocardiographic findings between before and 9 months after endomyocardial biopsy, the low TNC group was associated with decreased LV end-diastolic diameter and increased LV ejection fraction, whereas the high TNC group was not. Survival analysis revealed a worse outcome in the high TNC group than in the low TNC group (P < 0.001). Multivariable Cox regression analysis revealed that TNC area was independently associated with poor outcome (HR = 1.347, P = 0.032). Conclusions Increased myocardial TNC expression was associated with worse LV remodeling and long-term outcome in DCM
Phase diagram and magnetocaloric effect of CoMnGe_{1-x}Sn_{x} alloys
We propose the phase diagram of a new pseudo-ternary compound,
CoMnGe_{1-x}Sn_{x}, in the range x less than or equal to 0.1. Our phase diagram
is a result of magnetic and calometric measurements. We demonstrate the
appearance of a hysteretic magnetostructural phase transition in the range
x=0.04 to x=0.055, similar to that observed in CoMnGe under hydrostatic
pressure. From magnetisation measurements, we show that the isothermal entropy
change associated with the magnetostructural transition can be as high as 4.5
J/(K kg) in a field of 1 Tesla. However, the large thermal hysteresis in this
transition (~20 K) will limit its straightforward use in a magnetocaloric
device.Comment: 12 pages, 5 figure
SDW and FISDW transition of (TMTSF)ClO at high magnetic fields
The magnetic field dependence of the SDW transition in (TMTSF)ClO for
various anion cooling rates has been measured, with the field up to 27T
parallel to the lowest conductivity direction . For quenched
(TMTSF)ClO, the SDW transition temperature increases
from 4.5K in zero field up to 8.4K at 27T. A quadratic behavior is observed
below 18T, followed by a saturation behavior. These results are consistent with
the prediction of the mean-field theory. From these behaviors,
is estimated as =13.5K for the perfect nesting case. This
indicates that the SDW phase in quenched (TMTSF)ClO, where is less than 6K, is strongly suppressed by the two-dimensionality of
the system. In the intermediate cooled state in which the SDW phase does not
appear in zero field, the transition temperature for the field-induced SDW
shows a quadratic behavior above 12T and there is no saturation behavior even
at 27T, in contrast to the FISDW phase in the relaxed state. This behavior can
probably be attributed to the difference of the dimerized gap due to anion
ordering.Comment: 4pages,5figures(EPS), accepted for publication in PR
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