TY - JOUR
T1 - Reappearance of first Shapiro step in narrow topological Josephson junctions
AU - Rosenbach, Daniel
AU - Schmitt, Tobias W.
AU - Schüffelgen, Peter
AU - Stehno, Martin P.
AU - Li, Chuan
AU - Schleenvoigt, Michael
AU - Jalil, Abdur R.
AU - Mussler, Gregor
AU - Neumann, Elmar
AU - Trellenkamp, Stefan
AU - Golubov, Alexander A.
AU - Brinkman, Alexander
AU - Grützmacher, Detlev
AU - Schäpers, Thomas
N1 - Funding Information:
This work was financially supported by the Virtual Institute for Topological Insulators (VITI), which is funded by the Helmholtz Association (VH-VI-511). This work was financially supported by the Netherlands Organization for Scientific Research (NWO) through a VENI grant (680-47-463). This work was financially supported by the German Federal Ministry of Education and Research (BMBF) via the Quantum Futur project "MajoranaChips" (Grant No. 13N15264) within the funding program Photonic Research Germany. This work was partly funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy-Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) EXC 2004/1 - 390534769.
Publisher Copyright:
Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science.
PY - 2021/6/23
Y1 - 2021/6/23
N2 - In Josephson junctions, a supercurrent across a nonsuperconducting weak link is carried by electron-hole bound states. Because of the helical spin texture of nondegenerate topological surface states, gapless bound states are established in junctions with topological weak link. These have a characteristic 4π-periodic current phase relation (CφR) that leads to twice the conventional Shapiro step separation voltage in radio frequency-dependent measurements. In this context, we identify an attenuated first Shapiro step in (Bi0.06Sb0.94)2Te3 (BST) Josephson junctions with AlOx capping layer. We further investigate junctions on narrow, selectively deposited BST nanoribbons, where surface charges are confined to the perimeter of the nanoribbon. Within these junctions, previously identified signatures of gapless bound states are absent. Because of confinement, transverse momentum sub-bands are quantized and a topological gap opening is observed. Surface states within these quantized sub-bands are spin degenerate, which evokes bound states of conventional 2π-periodic CφR within the BST nanoribbon weak link.
AB - In Josephson junctions, a supercurrent across a nonsuperconducting weak link is carried by electron-hole bound states. Because of the helical spin texture of nondegenerate topological surface states, gapless bound states are established in junctions with topological weak link. These have a characteristic 4π-periodic current phase relation (CφR) that leads to twice the conventional Shapiro step separation voltage in radio frequency-dependent measurements. In this context, we identify an attenuated first Shapiro step in (Bi0.06Sb0.94)2Te3 (BST) Josephson junctions with AlOx capping layer. We further investigate junctions on narrow, selectively deposited BST nanoribbons, where surface charges are confined to the perimeter of the nanoribbon. Within these junctions, previously identified signatures of gapless bound states are absent. Because of confinement, transverse momentum sub-bands are quantized and a topological gap opening is observed. Surface states within these quantized sub-bands are spin degenerate, which evokes bound states of conventional 2π-periodic CφR within the BST nanoribbon weak link.
KW - UT-Gold-D
UR - http://www.scopus.com/inward/record.url?scp=85108718166&partnerID=8YFLogxK
U2 - 10.1126/sciadv.abf1854
DO - 10.1126/sciadv.abf1854
M3 - Article
C2 - 34162537
AN - SCOPUS:85108718166
SN - 2375-2548
VL - 7
JO - Science advances
JF - Science advances
IS - 26
M1 - eabf1854
ER -