Bulk-free topological insulator BiSe nanoribbons with magnetotransport signatures of Dirac surface states.

Many applications of topological insulators (TIs) as well as new phenomena require devices with reduced dimensions. While much progress has been made to realize thin films of TIs with low bulk carrier densities, nanostructures have not yet been reported with similar properties, despite the fact that reduced dimensions should help diminish the contributions from bulk carriers. Here we demonstrate that BiSe nanoribbons, grown by a simple catalyst-free physical-vapour deposition, have inherently low bulk carrier densities, and can be further made bulk-free by thickness reduction, thus revealing the high mobility topological surface states.

Author Correction: Induced unconventional superconductivity on the surface states of BiTe topological insulator.

The original version of this Article contained an error in Fig. 6b. In the top scattering process, while the positioning of both arrows was correct, the colours were switched: the first arrow was red and the second arrow was blue, rather than the correct order of blue then red.

Author Correction: Induced unconventional superconductivity on the surface states of BiTe topological insulator.

The original version of this Article omitted the following from the Acknowledgements:"This work was partly supported by the Research Council of Norway through its Centres of Excellence funding scheme, project number 262633, QuSpin."This has now been corrected in both the PDF and HTML versions of the article.

Induced unconventional superconductivity on the surface states of BiTe topological insulator.

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  + ip wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using BiTe topological insulator.

Room Temperature Electrical Detection of Spin Polarized Currents in Topological Insulators.

Topological insulators (TIs) are a new class of quantum materials that exhibit a current-induced spin polarization due to spin-momentum locking of massless Dirac Fermions in their surface states. This helical spin polarization in three-dimensional (3D) TIs has been observed using photoemission spectroscopy up to room temperatures. Recently, spin polarized surface currents in 3D TIs were detected electrically by potentiometric measurements using ferromagnetic detector contacts.

Express optical analysis of epitaxial graphene on SiC: impact of morphology on quantum transport.

We show that inspection with an optical microscope allows surprisingly simple and accurate identification of single and multilayer graphene domains in epitaxial graphene on silicon carbide (SiC/G) and is informative about nanoscopic details of the SiC topography, making it ideal for rapid and noninvasive quality control of as-grown SiC/G. As an illustration of the power of the method, we apply it to demonstrate the correlations between graphene morphology and its electronic properties by quantum magneto-transport.

Antibiotic resistance plasmids spread among natural isolates of Escherichia coli in spite of CRISPR elements.

Clustered, regularly interspaced, short palindromic repeats (CRISPRs) are implicated in defence against foreign DNA in various archaeal and bacterial species. They have also been associated with a slower spread of antibiotic resistance. However, experimental and evolutionary studies raise doubts about the role of CRISPRs as a sort of immune system in Escherichia coli.

Antibiotic resistance plasmids spread among natural isolates of Escherichia coli in spite of CRISPR elements.

Clustered, regularly interspaced, short palindromic repeats (CRISPRs) are implicated in defence against foreign DNA in various archaeal and bacterial species. They have also been associated with a slower spread of antibiotic resistance. However, experimental and evolutionary studies raise doubts about the role of CRISPRs as a sort of immune system in Escherichia coli.

CRISPR distribution within the Escherichia coli species is not suggestive of immunity-associated diversifying selection.

In order to get further insights into the role of the clustered, regularly interspaced, short palindromic repeats (CRISPRs) in Escherichia coli, we analyzed the CRISPR diversity in a collection of 290 strains, in the phylogenetic framework of the strains represented by multilocus sequence typing (MLST). The set included 263 natural E. coli isolates exposed to various environments and isolated over a 20-year period from humans and animals, as well as 27 fully sequenced strains.