1,846 research outputs found
Theory of quasiparticle interference in mirror symmetric 2D systems and its application to surface states of topological crystalline insulators
We study symmetry protected features in the quasiparticle interference (QPI)
pattern of 2D systems with mirror symmetries and time-reversal symmetry, around
a single static point impurity. We show that, in the Fourier transformed local
density of states (FT-LDOS), \rho(\bq,\omega), while the position of high
intensity peaks generically depends on the geometric features of the iso-energy
contour at energy , the \emph{absence} of certain peaks is guaranteed
by the opposite mirror eigenvalues of the two Bloch states that are (i) on the
mirror symmetric lines in the Brillouin zone (BZ) and (ii) separated by
scattering vector \bq. We apply the general result to the QPI on the -surface of topological crystalline insulator PbSnTe and predict
all vanishing peaks in \rho(\bq,\omega). The model-independent analysis is
supported by numerical calculations using an effective four-band model derived
from symmetry analysis.Comment: Six-page text plus 2.5-page appendices, three figures and one table.
Accepted versio
Exotic Superconducting Properties in Topological Nodal Semimetal PbTaSe
We report the electronic properties of superconductivity in the topological
nodal-line semimetal PbTaSe. Angle-resolved photoemission measurements
accompanied by band calculations confirmed the nodal-line band structure in the
normal state of single crystalline PbTaSe. Resistivity,
magnetic-susceptibility and specific heat measurements have also been performed
on high-quality single crystals. We observed upward features and large
anisotropy in upper critical field () measured in-plane
(H//\textbf{ab}) and out-plane (H//\textbf{c}), respectively. Especially,
measured in H//\textbf{ab} shows sudden upward features rather than a
signal of saturation in ultralow temperatures. The specific heat measurements
under magnetic field reveal a full superconducting gap with no gapless nodes.
These behaviors in this clean noncentrosymmetric superconductor is possibly
related to the underlying exotic physics, providing important clue for
realization of topological superconductivity.Comment: 6 pages, 5 figures,1 table;Accepted for publication on PR
Two distinct topological phases in the mixed valence compound YbB6 and its differences from SmB6
We discuss the evolution of topological states and their orbital textures in
the mixed valence compounds SmB6 and YbB6 within the framework of the
generalized gradient approximation plus onsite Coulomb interaction (GGA+U)
scheme for a wide range of values of U. In SmB6, the topological Kondo
insulator (TKI) gap is found to be insensitive to the value of U, but in sharp
contrast, Kondo physics in isostructural YbB6 displays a surprising sensitivity
to U. In particular, as U is increased in YbB6, the correlated TKI state in the
weak-coupling regime transforms into a d-p-type topological insulator phase
with a band inversion between Yb-5d and B-2p orbitals in the intermediate
coupling range, without closing the insulating energy gap throughout this
process. Our theoretical predictions related to the TKI and non-TKI phases in
SmB6 and YbB6 are in substantial accord with recent angle-resolved
photoemission spectroscopy (ARPES) experiments.Comment: 6 pages, 4 figures URL:
http://link.aps.org/doi/10.1103/PhysRevB.91.15515
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