arXiv subjects

Wei-Cheng Bao

Publications and source records attributed to Wei-Cheng Bao.

2 recordsLinked to original sources

arXiv2020

Observation of discrete conventional Caroli-de Gennes-Matricon states in the vortex core of single-layer FeSe/SrTiO3

Using low-temperature scanning tunneling microscopy (STM), we studied the vortex states of single-layer FeSe film on SrTiO3 (100) substrate, and the local behaviors of superconductivity at sample boundaries. We clearly observed multiple discrete Caroli-de Gennes-Matricon (CdGM) states in the vortex core, and quantitative analysis shows their energies well follow the formula: E = μΔ^2/E_F, where μ is a half integer and Δ is the mean superconducting gap over the Fermi surface. Meanwhile, a fully gapped spectrum without states near zero bias is observed at [110](Fe) oriented boundary of 1 ML and 2 ML FeSe films, and atomic step edge of 1 ML FeSe. Accompanied with theoretical calculations, our results indicate a s-wave pairing without sign-change in the high-TC FeSe_SrTiO3 superconductor.

cond-mat.supr-con↗

arXiv2018

Visualizing the $d$-vector in a nematic triplet superconductor

Recent experiments show strong evidences of nematic triplet superconductivity in doped Bi$_2$Se$_3$ and in Bi$_2$Te$_3$ thin film on a superconducting substrate, but with varying identifications of the direction of the $d$-vector of the triplet that is essential to the topology of the underlying superconductivity. Here we show that the $d$-vector can be directly visualized by scanning tunneling measurements: At subgap energies the $d$-vector is along the leading peak wave-vector in the quasi-particle-interference pattern for potential impurities, and counter-intuitively along the elongation of the local density-of-state profile of the vortex. The results provide a useful guide to experiments, the result of which would in turn pose a stringent constraint on the pairing symmetry.

cond-mat.supr-con↗