10 research outputs found
Evidence for Majorana bound state in an iron-based superconductor
The search for Majorana bound state (MBS) has recently emerged as one of the
most active research areas in condensed matter physics, fueled by the prospect
of using its non-Abelian statistics for robust quantum computation. A highly
sought-after platform for MBS is two-dimensional topological superconductors,
where MBS is predicted to exist as a zero-energy mode in the core of a vortex.
A clear observation of MBS, however, is often hindered by the presence of
additional low-lying bound states inside the vortex core. By using scanning
tunneling microscope on the newly discovered superconducting Dirac surface
state of iron-based superconductor FeTe1-xSex (x = 0.45, superconducting
transition temperature Tc = 14.5 K), we clearly observe a sharp and non-split
zero-bias peak inside a vortex core. Systematic studies of its evolution under
different magnetic fields, temperatures, and tunneling barriers strongly
suggest that this is the case of tunneling to a nearly pure MBS, separated from
non-topological bound states which is moved away from the zero energy due to
the high ratio between the superconducting gap and the Fermi energy in this
material. This observation offers a new, robust platform for realizing and
manipulating MBSs at a relatively high temperature.Comment: 27 pages, 11 figures, supplementary information include
Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor
Majorana zero-modes (MZMs) are spatially-localized zero-energy fractional
quasiparticles with non-Abelian braiding statistics that hold a great promise
for topological quantum computing. Due to its particle-antiparticle
equivalence, an MZM exhibits robust resonant Andreev reflection and 2e2/h
quantized conductance at low temperature. By utilizing variable-tunnel-coupled
scanning tunneling spectroscopy, we study tunneling conductance of vortex bound
states on FeTe0.55Se0.45 superconductors. We report observations of conductance
plateaus as a function of tunnel coupling for zero-energy vortex bound states
with values close to or even reaching the 2e2/h quantum conductance. In
contrast, no such plateau behaviors were observed on either finite energy
Caroli-de Genne-Matricon bound states or in the continuum of electronic states
outside the superconducting gap. This unique behavior of the zero-mode
conductance reaching a plateau strongly supports the existence of MZMs in this
iron-based superconductor, which serves as a promising single-material platform
for Majorana braiding at a relatively high temperature
Identification and Validation of Glycosyltransferases Correlated with Cuproptosis as a Prognostic Model for Colon Adenocarcinoma
Cuproptosis is a newly defined programmed cell death pattern and is believed to play an important role in tumorigenesis and progression. In addition, many studies have shown that glycosylation modification is of vital importance in tumor progression. However, it remains unclear whether glycosyltransferases, the most critical enzymes involved in glycosylation modification, are associated with cuproptosis. In this study, we used bioinformatic methods to construct a signature of cuproptosis-related glycosyltransferases to predict the prognosis of colon adenocarcinoma patients. We found that cuproptosis was highly correlated with four glycosyltransferases in COAD, and our model predicted the prognosis of COAD patients. Further analysis of related functions revealed the possibility that cuproptosis-related glycosyltransferase Exostosin-like 2 (EXTL2) participated in tumor immunity