Drive the Dirac electrons into Cooper pairs in Sr<sub>x</sub>Bi<sub>2</sub>Se<sub>3</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 28198378.
- Also identified by DOI 10.1038/ncomms14466 and PMC identifier 5316857.
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Abstract
Topological superconductors are a very interesting and frontier topic in condensed matter physics. Despite the tremendous efforts in exploring topological superconductivity, its presence is however still under heavy debate. The Dirac electrons have been proven to exist on the surface of a topological insulator. It remains unclear whether and how the Dirac electrons fall into Cooper pairing in an intrinsic superconductor with the topological surface states. Here we show the systematic study of scanning tunnelling microscope/spectroscopy on the possible topological superconductor Sr<sub>x</sub>Bi<sub>2</sub>Se<sub>3</sub>. We first demonstrate that only the intercalated Sr atoms can induce superconductivity. Then we show the full superconducting gaps without any in-gap density of states as expected theoretically for a bulk topological superconductor. Finally, we find that the surface Dirac electrons will simultaneously condense into the superconducting state within the superconducting gap. This vividly demonstrates how the surface Dirac electrons are driven into Cooper pairs.