65 research outputs found
Observation of a Dirac nodal line in AlB2
We have performed angle-resolved photoemission spectroscopy of AlB2 which is
isostructural to high-temperature superconductor MgB2. Using soft-x-ray
photons, we accurately determined the three-dimensional bulk band structure and
found a highly anisotropic Dirac-cone band at the K point in the bulk hexagonal
Brillouin zone. This band disperses downward on approaching the H point while
keeping its degeneracy at the Dirac point, producing a characteristic Dirac
nodal line along the KH line. We also found that the band structure of AlB2 is
regarded as a heavily electron-doped version of MgB2 and is therefore well
suited for fully visualizing the predicted Dirac nodal line. The present
results suggest that (Al,Mg)B2 system is a promising platform for studying the
interplay among Dirac nodal line, carrier doping, and possible topological
superconducting properties.Comment: 6 pages, 3 figure
Height Constitutes an Important Predictor of Mortality in End-Stage Renal Disease
Aim. Height is an important determinant of augmentation index (AI) that anticipates cardiovascular prognosis. There is a scanty of the data whether short height predicts survival in patients with end-stage renal diseases, a high risk population. Methods. Fifty two hypertensive patients with type 2 diabetic nephropathy receiving hemodialysis and 52 patients with nondiabetic nephropathy were enrolled. In addition to AI estimated with radial artery tonometry, classical cardiovascular risk factors were considered. Patients were followed for 2 years to assess cardiovascular prognosis. Results. Cox hazards regression revealed that both smoking and shortness in height independently contributed to total mortality and indicated that smoking as well as the presence of left ventricular hypertrophy predicted cardiovascular mortality. Our findings implicated that high AI, the presence of diabetes, and low high-density lipoprotein cholesterol were significant contributors to cardiovascular events. Conclusions. Our findings provide new evidence that shortness in height independently contributes to total mortality in hemodialysis patients
Unusual surface states associated with the PT-symmetry breaking and antiferromagnetic band folding in NdSb
We have performed micro-focused angle-resolved photoemission spectroscopy on
NdSb which exhibits the type-I antiferromagnetism below TN = 16 K. We succeeded
in selectively observing the band structure for all the three types of single-q
antiferromagnetic (AF) domains at the surface. We found that the two of three
surfaces whose AF-ordering vector lies within the surface plane commonly show
two-fold-symmetric surface states (SSs) around the bulk-band edges, whereas the
other surface with an out-of-plane AF-ordering vector displays
four-fold-symmetric shallow electronlike SS at the Brillouin-zone center. We
suggest that these SSs commonly originate from the combination of the PT
(space-inversion and time-reversal) symmetry breaking at the surface and the
band folding due to the AF order. The present results pave a pathway toward
understanding the relationship between the symmetry and the surface electronic
states in antiferromagnets.Comment: 20 pages, 5 figure
On Aharonov-Bohm oscillation in a ferromagnetic ring
Aharonov-Bohm effect in a ferromagnetic thin ring in diffusive regime is
theoretically studied by calculating the Cooperon and Diffuson. In addition to
the spin-orbit interaction, we include the spin-wave excitation and the spin
splitting, which are expected to be dominant sources of dephasing in
ferromagnets at low temperatures. The spin splitting turns out to kill the
spin-flip channel of Cooperon but leaves the spin-conserving channel untouched.
For the experimental confirmation of interference effect (described by
Cooperons) such as weak localization and Aharonov-Bohm oscillation with period
, we need to suppress the dominant dephasing by orbital motion. To do
this we propose experiments on a thin film or thin ring with magnetization and
external field perpendicular to the film, in which case the effective field
inside the sample is equal to the external field (magnetization does not add
up). The field is first applied strong enough to saturate the magnetization and
then carrying out the measurement down to zero field keeping the magnetization
nearly saturated, in order to avoid domain formations (negative fields may also
be investigated if the coercive field is large enough)
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