Proximity-Induced Odd-Frequency Superconductivity in a Topological Insulator

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Superconductivity at topological insulator (TI) and superconductor (SC) interfaces is predicted to exhibit novel correlations.
• An s-wave SC proximity coupled to a TI can induce superconductivity with a p-wave component.

Purpose of the Study:

• To experimentally investigate the proximity-induced superconducting state at a TI-SC interface.
• To provide evidence for novel superconducting correlations, specifically odd-frequency superconductivity.

Main Methods:

• Fabrication of a thin layer of the topological insulator Bi_{2}Se_{3} coupled to a conventional superconductor Nb.
• Depth-resolved magnetic field measurements below the superconducting transition temperature of Nb.

Main Results:

• Observation of a local magnetic field enhancement in Bi_{2}Se_{3} exceeding the externally applied field.
• Experimental evidence supporting an intrinsic paramagnetic Meissner effect, indicative of an odd-frequency superconducting state.
• Theoretical calculations confirm the presence of this novel superconducting component at the interface and extending into the TI.

Conclusions:

• The study presents the first observation of bulk odd-frequency superconductivity in a topological insulator.
• The topological insulator-superconductor interface serves as a promising platform for generating and studying novel superconducting states.
• The observed state is topologically distinct from conventional Bardeen-Cooper-Schrieffer superconductivity.