123 research outputs found
The wavefunction reconstruction effects in calculation of DM-induced electronic transition in semiconductor targets
The physics of the electronic excitation in semiconductors induced by sub-GeV
dark matter (DM) have been extensively discussed in literature, under the
framework of the standard plane wave (PW) and pseudopotential calculation
scheme. In this paper, we investigate the implication of the all-electron (AE)
reconstruction on estimation of the DM-induced electronic transition event
rates. As a benchmark study, we first calculate the wavefunctions in silicon
and germanium bulk crystals based on both the AE and pseudo (PS) schemes within
the projector augmented wave (PAW) framework, and then make comparisons between
the calculated excitation event rates obtained from these two approaches. It
turns out that in process where large momentum transfer is kinetically allowed,
the two calculated event rates can differ by a factor of a few. Such
discrepancies are found to stem from the high-momentum components neglected in
the PS scheme. It is thus implied that the correction from the AE wavefunction
in the core region is necessary for an accurate estimate of the DM-induced
transition event rate in semiconductors.Comment: A missing factor associated with the Fourier
transformation is added to both the AE and PS event rates in this version.
The ratio between the AE and PS event rates is not affecte
Topological crystalline antiferromagnetic state in tetragonal FeS
Integration between magnetism and topology is an exotic phenomenon in
condensed-matter physics. Here, we propose an exotic phase named topological
crystalline antiferromagnetic state, in which antiferromagnetism intrinsically
integrates with nontrivial topology, and we suggest such a state can be
realized in tetragonal FeS. A combination of first-principles calculations and
symmetry analyses shows that the topological crystalline antiferromagnetic
state arises from band reconstruction induced by pair checker-board
antiferromagnetic order together with band-gap opening induced by intrinsic
spin-orbit coupling in tetragonal FeS. The topological crystalline
antiferromagnetic state is protected by the product of fractional translation
symmetry, mirror symmetry, and time-reversal symmetry, and present some unique
features. In contrast to strong topological insulators, the topological
robustness is surface-dependent. These findings indicate that non-trivial
topological states could emerge in pure antiferromagnetic materials, which
sheds new light on potential applications of topological properties in
fast-developing antiferromagnetic spintronics.Comment: 8 pages, 6 figure
Fractional quantum Hall effect of topological surface states under a strong tilted magnetic field
The fractional quantum Hall effect (FQHE) of topological surface-state
particles under a tilted strong magnetic field is theoretically studied by
using the exact diagonalization method. The Haldane's pseudopotentials for the
Coulomb interaction are analytically obtained. The results show that by
increasing the in-plane component of the tilted magnetic field, the FQHE state
at =0 Landau level (LL) becomes more stable, while the stabilities of
= LLs become weaker. Moreover, we find that the excitation gaps of the
FQHE states increase as the tilt angle is increased.Comment: 4.2 pages, 4 figure
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