Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p
x + ip
y wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral p
x + ip
y component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and π coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.
Chiral
nanomaterials have drawn extensive attention on account
of numerous application prospects in optoelectronics, asymmetric catalysis,
chiral recognition, and three-dimensional (3D) display. Thereinto,
chiral perovskite has been a hotspot due to brilliant optoelectronic
properties, but some problems limit the development, including low
quantum yield, low chiral intensity, and the lack of facile regulation.
To overcome these issues, an effective ligand exchange strategy, i.e. the interface modification has been proposed for chiral
perovskite nanocrystals (PNCs). With the surface modification of CsPbBr3 PNCs with chiral organic ammonium in methyl acetate in the
typical purification process, excellent circular dichroism (CD) signals
were obtained and defects were eliminated, leading to an increase
in the photoluminescence quantum yield (PLQY) from 50% to nearly 100%.
The CD signal can be regulated through a ligand exchange strategy
in the longitudinal dimension, the chiral intensity, and the transverse
dimension, the wavelength range. Here, the proper addition of R-α-PEAI
into the R-α-PEABr-capped CsPbBr3 PNCs can produce
a superstrong CD signal with the highest anisotropy factor (g-factor) of 0.0026 in the visible region among reported
chiral colloidal PNCs. Simultaneously, the luminescence emission can
be tuned from the green to red region with boosted PLQY through the
approach. The density functional theory (DFT) calculation result supports
that chirality comes from the hybridization between the energy level
of a perovskite structure and that of chiral organic molecules. These
properties can be used in the structural engineering of high-performance
chiral optical materials, spin-polarized light-emitting devices, and
polarized optoelectronic devices.
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