Pseudogap and proximity effect in the Bi2Te3/Fe1+yTe interfacial superconductor

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Two-dimensional superconductivity near topological insulator surface states is crucial for realizing topological superconductivity.
• Topological superconductors are of significant interest for their potential to host Majorana fermionic states.

Purpose of the Study:

• To investigate the novel Bi2Te3/Fe1+yTe interfacial superconductor.
• To explore the nature of superconductivity at the interface between a topological insulator and a magnetic superconductor.

Main Methods:

• Directional point-contact spectroscopy was employed.
• The study focused on a Bi2Te3 film (9 quintuple layers) epitaxially grown on Fe1+yTe via van der Waals bonding.

Main Results:

• Highly unconventional superconductivity was observed, characterized by a complex twin-gap structure.
• A pseudogap persists up to 40 K, replacing the larger gap above ~12 K.
• The larger gap exhibits unconventional order parameter symmetry, attributed to proximity effects from a FeTe layer.
• The smaller gap is linked to induced superconductivity in the topological insulator Bi2Te3.

Conclusions:

• The Bi2Te3/Fe1+yTe interface hosts complex, unconventional superconductivity.
• The findings suggest the potential for proximity-induced superconductivity in topological insulators.
• This system offers a promising platform for exploring topological superconducting states and Majorana fermions.