Abstract

Superconducting topological systems formed by a strong 3D topological insulator (TI) in proximity to a conventional s-wave superconductor (SC) have been intensely studied, as they may host Majorana zero modes. However, there are limited experimental realizations of TI-SC systems in which robust superconducting pairing is induced on the surface states of the TI and a topological superconducting state is established. Here, we fabricate a TI-SC system by depositing, via a focused ion beam, tungsten (W) nanoscale clusters on the surface of TI Bi_0.91Sb_0.09. We find that the resulting heterostructure supports phase-slip lines (PSLs) that act as effective Josephson junctions (JJs). Here, we probe the response of the system to microwave radiation. We find that for some ac frequencies, and powers, the resulting Shapiro steps’ structure of the voltage–current characteristic exhibits a missing first step and an unexpectedly wide second Shapiro step. The theoretical analysis of the measurements shows that the unusual Shapiro response arises from the interplay between a static JJ and a dynamic one and allows us to identify the conditions under which the missing first step can be attributed to the topological nature of the JJs formed by the PSLs. Our results suggest an approach to induce superconductivitymore » in a TI, a route to realizing highly transparent topological JJs, and show how the response of superconducting systems to microwave radiation can be used to infer the dynamics of PSLs. Highly transparent topological junctions are promising candidates to realize vector field sensors with very high sensitivity. In addition, due to the nontrivial Berry phase of the TI’s surface states such junctions can be in a topological state which is ideal to create topologically protected qubits.« less

Authors:

Qu, Dong-Xia  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-7623-4207"

Cuozzo, Joseph J. ^[2]; Teslich, Nick E. ^[1]; Ray, Keith G.  ^[1];

• Search DOE PAGES for author "Ray, Keith G."
• Search DOE PAGES for ORCID "0000-0002-6241-7472"

Dai, Zurong ^[1]; Li, Tian T.  ^[1];

• Search DOE PAGES for author "Li, Tian T."
• Search DOE PAGES for ORCID "0000-0003-2409-5799"

Chapline, George F. ^[1]; DuBois, Jonathan L. ^[1]; Rossi, Enrico ^[3]

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+ Show Author Affiliations

1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
2. Sandia National Laboratories (SNL-CA), Livermore, CA (United States); College of William and Mary, Williamsburg, VA (United States)
3. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); College of William and Mary, Williamsburg, VA (United States)

Publication Date:

Wed Feb 07 00:00:00 EST 2024

Research Org.:

Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); College of William and Mary, Williamsburg, VA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

2326301

Alternate Identifier(s):

OSTI ID: 2335563

Report Number(s):

SAND-2024-03247J; LLNL-JRNL-843054
Journal ID: ISSN 2574-0970

Grant/Contract Number:  

NA0003525; AC52-07NA27344; SC0022245; 19-LW-040

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Nano Materials

Additional Journal Information:

Journal Volume: 7; Journal Issue: 4; Journal ID: ISSN 2574-0970

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Topological insulator; topological superconductor; topological qubit; phase-slip lines; AC Josephson effect; Majorana zero modes; topological quantum computation; topological insulator