6 research outputs found
Quantum oscillations of the magnetic torque in the nodal-line Dirac semimetal ZrSiS
We report a study of quantum oscillations (QO) in the magnetic torque of the
nodal-line Dirac semimetal ZrSiS in the magnetic fields up to 35 T and the
temperature range from 40 K down to 2 K, enabling high resolution mapping of
the Fermi surface (FS) topology in the (Z-R-A) plane of the first
Brillouin zone (FBZ). It is found that the oscillatory part of the measured
magnetic torque signal consists of low frequency (LF) contributions
(frequencies up to 1000 T) and high frequency (HF) contributions (several
clusters of frequencies from 7-22 kT). Increased resolution and angle-resolved
measurements allow us to show that the high oscillation frequencies originate
from magnetic breakdown (MB) orbits involving clusters of individual
hole and electron pockets from the diamond shaped FS in the Z-R-A
plane. Analyzing the HF oscillations we have unequivocally shown that the QO
frequency from the dog-bone shaped Fermi pocket ( pocket) amounts
T. Our findings suggest that most of the frequencies in the LF
part of QO can also be explained by MB orbits when intraband tunneling in the
dog-bone shaped electron pocket is taken into account. Our results give
a new understanding of the novel properties of the FS of the nodal-line Dirac
semimetal ZrSiS and sister compounds
Multiband Photometry Evolution in the First Weeks of SN 2023ixf, a possible II-L Subtype Supernova
Multiband photometric observations and their evaluation to instrumental
magnitudes were performed using standard Johnson-Cousins filters (B, V, Rc) as
well r and g Sloan filters, and not standard ones (R, G, B, and Clear filters).
These were recorded from 9 observatories and from the MicroObservatory Robotic
Telescope Network. The results describe the rapid ascent towards the maximum
(2.5 magnitudes about in five days in the B filter) and the slow decrease after
the maximum (0.0425 +/- 0.02 magnitudes/day in the B filter). The results
highlight the strong variation of the B-V colour indices during the first 50
days (from -0.20 +/- 0.02 to +0.85 +/- 0.02) and V-R (from 0 +/- 0.01 to +0.50
+/- 0.01) after the explosion, presumably corresponding to the cooling of the
stellar photosphere. At 50 days after the explosion the magnitude decrease from
the maximum was observed to continue where it faded by 2.5 magnitudes (B
filter), thus we propose SN 2023ixf is a Type II, subtype L, supernova (SNe)
Optical conductivity of the type-II Weyl semimetal TaIrTe<sup>4</sup>
TaIrTe4 is an example of a candidate Weyl type-II semimetal with a minimal possible number of Weyl nodes. Four nodes are reported to exist in a single plane in k space. The existence of a conical dispersion linked toWeyl nodes has yet to be shown experimentally. Here, we use optical spectroscopy as a probe of the band structure on a low-energy scale. Studying optical conductivity allows us to probe intraband and interband transitions with zero momentum. In TaIrTe4, we observe a narrow Drude contribution and an interband conductivity that may be consistent with a tilted linear band dispersion up to 40 meV. The interband conductivity allows us to establish the effective parameters of the conical dispersion; effective velocity v = 1.1 Ă— 104 m/s and tilt Îł = 0.37. The transport data, Seebeck and Hall coefficients, are qualitatively consistent with conical features in the band structure. Quantitative disagreement may be linked to the multiband nature of TaIrTe4